2001 Saturn SL1 Mod Thread
 

I've been on staycation this week and have devoted a fair bit of time to starting the ecomods on my 2001 Saturn SL1. I'll use this thread to describe each modification. There isn't going to be an A-B-A testing of individual mods, but there will be A-A-A-A-B-B-B-B-... tests of each group of mods.

The mods I completed this week are:

• Fixed fender-to-bumper gap caused by drooping bumpger
• Sealed gaps around hood
• Extended air dam most of the way to the wheels
• Completely enclosed the front grill

I'll write a separate post for each mod.

2001 Saturn SL1 Mod - Fix Gap Caused by Drooping Bumper
 

Apparently this is common problem with Saturns. The bumper cover, which is one large plastic piece that wraps all the way around to the wheel wells, is held on by three bolts on each side. Quite a bit of it (probably the vast majority of it by weight), hangs out past the front-most bolts, and over time, it begins to sag, causing an unsightly gap at the front:

http://ecomodder.com/forum/attachmen...1&d=1502115483

To fix this, I undid the front bolt on one side (after removing the headlight assembly), inserted a piece of cardboard, and traced around the fender. I then cut out the resulting shape and checked that it would fit under the top lip of the bumper. A local metal shop then cut me two pieces of 1/8" steel in the same shape (for a total cost of $12):

http://ecomodder.com/forum/attachmen...1&d=1502069341

I simply bolted these pieces in place, leaving out the flat washer that was there before, but retaining the lock washer:

http://ecomodder.com/forum/attachmen...1&d=1502069642

Creeeeepy:

http://ecomodder.com/forum/attachmen...1&d=1502069642

That took care of the problem at the sides. The center of the bumper cover is held to the frame by three plastic snap in fasteners, and there's a lot of free play. I replaced these with bolts and washers, tightening them down while lifting the front of the bumper cover:

http://ecomodder.com/forum/attachmen...1&d=1502069821

The last picture also shows some of the weather stripping I installed for gap sealing (to be covered in a separate post in this thread).

2001 Saturn SL1 Mod - Sealing the Gaps Around the Hood
 

This one was easy. I simply purchased a few rolls of good quality closed-cell foam weather stripping. I used 1/2"x1/2" over top of the head lights and center of the front bumper cover, as seen in the last photo from my previous post, and here:

http://ecomodder.com/forum/attachmen...1&d=1502113672

For the sides of the hood, I used 3/8"x3/8" tape, applied to the small horizontal lip (visible in the previous photo) on the inside of the fender:

http://ecomodder.com/forum/attachmen...1&d=1502113691

I also applied a small piece of foam to the outside edge of the headlight, since there was quite a large gap between it and the fender:

http://ecomodder.com/forum/attachmen...1&d=1502113691

2001 Saturn SL1 Mod - Air Dam Extension
 

The SL1 already has a front air dam which deflects air upward into the radiator. The resulting vacuum created behind it probably helps draw the air through the radiator. However, this air dam is only about 2/3 of the width of the car, and a lot of air can spill around it, where it has to flow through the suspension.

I started by making a cardboard template to figure out exactly the size and shape that I would need:

http://ecomodder.com/forum/attachmen...1&d=1502114524

After reading a lot of other modders' threads on air dams, I took a trip to Home Depot to find some suitable material. I didn't like any of the lawn edging I found, but then spotted something really interesting. It's called a KwicKan, and is basically a 48"x30"x1/16" sheet of tough recycled black plastic (polypropylene?) with some holes cut into it for handles. The idea is that you roll it up, insert it into a garbage bag, and let it go. It expands to turn the bag into a fairly rigid can. When it's full (e.g. of leaves), you pull the sheet out. It seemed to the be the perfect material for my planned mods, so I bought one ($12).

Using a yellow paint marker, I traced around my template, and cut out two copies of it, one the mirror image of the other (the KwicKan material is textured and printed on one side, and smooth on the other):

http://ecomodder.com/forum/attachmen...1&d=1502114524

To fasten the air dam extensions to the fender, I made brackets out of 1/16" aluminum, cut into to 1"x2" pieces, and bent so that the air dam mounting surfaces would be vertical:

http://ecomodder.com/forum/attachmen...1&d=1502114904

I used stainless steel 10-24 bolts, finishing washers, flat washers, and lock nuts, both to fasten the brackets to the fender, and to fasten the air dam extensions to the brackets and existing air dam:

http://ecomodder.com/forum/attachmen...1&d=1502114904

Here's how it turned out:

http://ecomodder.com/forum/attachmen...1&d=1502114904

I was careful to make both pieces exactly the same (except mirrored) so that they can be swapped left to right if I ever want the textured side outward (I'd have to paint them of course).

2001 Saturn SL1 Mod - Complete Grill Block
 

I've been driving my car for a few weeks now with the grill completely blocked using two pieces of foam pipe insulation. This was a temporary measure, so I could monitor the engine temperature to see if this would be detrimental. After finding that it was fine (the temperature never got above 91°C, same as before blocking it), I decided to do a more aerodynamic grill block, including the fog light pockets too.

I knew I wanted use the KwicKan material, but I pondered for quite a while on how to cut it to exactly the right shape. I finally arrived at the idea of constructing a template piece by piece, by taping narrow strips of thin cardboard across the grill, and marking the edges of each piece with where the edges of the template should be. A few pictures are worth a thousand words:

http://ecomodder.com/forum/attachmen...1&d=1502116268

http://ecomodder.com/forum/attachmen...1&d=1502116268

I used progressively narrower strips as the curvature got sharper, and at the end, I fitted in small pieces to match the curve:

http://ecomodder.com/forum/attachmen...1&d=1502116268

Before removing the template from the car, I applied clear packing tape over the whole thing to make sure none of the pieces could shift. I then connected the dots, using a spline for the very long nearly-straight curves, and a set of french curves near the ends:

http://ecomodder.com/forum/attachmen...1&d=1502116268

Next I cut out the template, traced around it onto the KwicKan material (one each way), and cut them out:

http://ecomodder.com/forum/attachmen...1&d=1502116268

http://ecomodder.com/forum/attachmen...1&d=1502116268

To mount the grill blocks, I again used brackets made from 1/16" aluminum, this time in 3/4"x2" pieces. The pieces had to be bent to various angles ranging from 55° to 93°. To facilitate bending them, I made a poor man's bending brake out of a hinge, a piece of wood, and my bench vice:

http://ecomodder.com/forum/attachmen...1&d=1502117325

The lower bracket for the fog light area needed to have its mounting surface curved slightly:

http://ecomodder.com/forum/attachmen...1&d=1502117325

I attached all the brackets to the bumper cover using 3M body side moulding mounting tape, after thoroughly cleaning everything with hot water and then rubbing alcohol. My car has teeth:

http://ecomodder.com/forum/attachmen...1&d=1502117325

My plan was to drill and thread holes in the brackets to take 10-32 bolts, but since I didn't have any handy, I drilled 3/32" holes and used stainless steel #4x1/2" self-tapping screws for now. I think I will order a bag of 10-32 black nylon bolts to replace these with eventually:

http://ecomodder.com/forum/attachmen...1&d=1502117325

At the ends, I used a single #8x2" screw, through a 1-1/4" long aluminum spacer, screwed into the black fake grill at the back of the fog light recess:

http://ecomodder.com/forum/attachmen...1&d=1502117325

http://ecomodder.com/forum/attachmen...1&d=1502117928

Here is the completed grill cover. I left approximately 6" open in the middle, because this would be covered by the license plate:

http://ecomodder.com/forum/attachmen...1&d=1502117928

And finally, here it's all done. The license plate has been installed over the opening, and the holes from the original license plate holder were plugged using the plugs from the bumper cover fasteners, painted to match the car, and press-fitted into the holes after drilling them out to 6.5mm:

http://ecomodder.com/forum/attachmen...1&d=1502117928

I'm back to work next week, so we'll see how it all works out as far as fuel economy goes.

I have a few more mods in mind, most notably wheel covers. I was going to make these using the fabric and fiberglass resin over snap in wheel cover technique, but now I want to see if I can heat form the KwicKan material to make black plastic pizza-pan covers instead.

Nice job fixing up and modding the SL1. :thumbup:

First partial tank result is in. I had burned 1/4 of a tank before doing these mods, and this morning, with 744km (462mi) since my last fill up, I put 38.3L (10.1USgal) into the tank, for a record fuel economy of 5.15L/100km (45.6mi/USgal, 54.8mi/ImpGal).

http://ecomodder.com/forum/attachmen...1&d=1502717781

I'm hoping for even better next fill-up, where the whole tank will be with the mods in place. After that, I'm going to put on smooth wheel covers.

http://ecomodder.com/forum/attachmen...1&d=1502717781

Brilliant work. And this is all done with no modifications to the vehicle's mechanical systems, just driving style and a little aero. That's really excellent.

Where does it pick the intake air from?

Excellent numbers from a 1.9 l engine!
Is it a lean burn engine?
I struggled a lot with my BMW 1.8 to see less than 6.3l\100Km..
Good job!!

Cooling air comes in from underneath, being deflected up into the radiator by the air dam. Even before the mods, that's where most of the cooling air came from. The engine air intake is just in front of the radiator (where it's always been).

Both coolant temperature (91°C) and intake temperature (same as ambient air temperature) are unchanged from what they were before the mods.

Thanks! It's just a regular engine, and I haven't done any tweaks to it (like messing with the ECU or fooling the sensors), nor do I plan to.

First full tank results are in: 5.19 L/100 km, 45.3 mpg (US), 54.4 mpg (Imp).

A tiny bit worse than the previous tank (of which only 3/4 was with the mods in place). However, my wife took the car on a 56km trip, where she did about 13% worse than my average for the tank according to Torque. She's actually a pretty eco driver, but it was really hot that day, and she had the A/C on the whole way. If I do the math and factor that out, then I was burning 5.13 L/100km for the rest of the tank.

My average since I began hypermiling 60 days ago is now: 5.35 L/100km, 43.9 mpg (US), 52.7 mpg (Imp).

I finished my smooth wheel covers, although I'm not totally happy with how they turned out. I think I'll probably go ahead and put them on now. I'd really like to get below 5.0 L/100km (above 47 mpg (US), 56.4 mpg (Imp)).

EDIT: Based on the numbers so far, the mods seemed to have given me about a 5-6% improvement.

Thats pretty darn good. :thumbup:

Great numbers!
What is your commute and average speed?

My commute is 45km each way, and typically takes 38 to 40 minutes, so 68 to 71 km/h. Most of it is at 85-90 km/h, with several stop signs and lights along the way. About 3-4 km is "city driving". I also drive into the city once or twice a week for shopping, so I get extra city driving on those days.

BTW, my "lifetime" (of my 2009 Garmin GPS) average speed while moving is 67 km/h.

This weekend, I put on the wheel covers:

http://ecomodder.com/forum/attachmen...1&d=1503970526

I'm not really happy with how they turned out. They were made using the cotton-over-snap-in-covers method, and although I had the fabric stretched drum tight, when the resin cured, the tension in the fabric was uneven, resulting in waves and bumps:

http://ecomodder.com/forum/attachmen...1&d=1503928055

I'm going to drive with them for a few tankfuls while I think about other ways to do this. One idea that came to mind was plastic (such as the KwicKan material) riveted to snap-in trim rings.

Just finished the first tank with the wheel covers on: 5.15 L/100 km, 45.69 mpg (US), 54.88 mpg (Imp).

Only marginally better than the previous tank (5.19 L/100km). On the bright side, I expected this tank to be pretty bad, since I did a higher than normal proportion of city driving this time. So maybe the wheel covers made up for it on the highway. Too soon to tell.

I've also got Torque working really well now. Its prediction of how much fuel I had left in the tank was exactly right.

Also, this was my first tank over 800km, and according to Torque, I averaged 4.7 L/100km (50 mpg US, 60 mpg Imp) on the 35km part of my commute from my house to the gas station this morning. Nothing like running on fumes to promote eco driving.

PS. This is fun!

Great to hear you're enjoying it. I agree, it is a lot of fun. Nice job too.

Another record setting tank. 825km on 40.06L for a fuel economy of 4.86 L/100 km, 48.45 mpg (US), 58.19 mpg (Imp). Torque came up with 5.07L/100km for this tank.

http://ecomodder.com/forum/attachmen...1&d=1505916603

Good stuff you're doing with this Saturn.. hope to recreate some of what you've done with mine!

I use the 0.005" plastic tarp material for a number of projects. Usually I bond some wire mesh between two layers of plastic sheet. A lip just above the rear window might help air flow too.

Tablet Dedicated to Torque
 

I've been so happy with Torque, that I decided to keep using it instead of building an MPGuino or similar. In fact, I decided to go out an by an inexpensive 7" tablet to install permanently in the car. The tablet I chose was an Acer Iconia One B1-780, which I picked up for $110 at Walmart.

I'll post some pictures once I've installed it, but in the mean time, here's a screenshot of the layout I've come up with:

http://ecomodder.com/forum/attachmen...1&d=1510326565

I have a darker version that kicks in at night.

I'll be using this primarily to run Torque, but also MapFactor Navigator (a great free off-line GPS app), and RocketPlayer (a music player app). I'm going to install it in place of my car stereo (the radio doesn't work anyway), and put in a small home-made amp to drive the speakers.

http://ecomodder.com/forum/attachmen...1&d=1510329170

Car ready Android tablets.

https://www.carjoying.com/1-din-andr...avigation.html

Seem to get good reviews.

Still working on the tablet installation. Radio is out, amp is built, but I still need to fabricate something to hold the tablet itself. I hope to finish that this weekend.

In the mean time, I've put my winter tires on the car. Before I did so, my fuel economy on the last couple of tanks has gone down a bit, I think due to lots of windy and/or rainy and/or cold weather. I expected it to get worse with the snow tires (it always has in the past).

However, as I was putting them on, I noticed that they had a max sidewall rating of 45psi, vs. the 35psi on my summer tires. I had the summers inflated to the full 35, and decided to try the snows at 40 for now. So far, for the first tank and a half, my fuel economy has improved by about 3% according to both Torque and calculations done at fill-up, despite the weather getting worse. This looks promising. I'm not sure I'll take them all the way to 45, since the ride is already getting a bit harsh.

I sort of finished the tablet install in the car last night ...

http://ecomodder.com/forum/attachmen...1&d=1511793201

Physically, it worked out well. The tablet fits the existing stereo opening almost exactly. I still need to black out the area behind the tablet, and I may make a front fascia for it to blend in better with the rest of the trim.

The tablet is held in place with strong magnets on the front face of the amplifier enclosure (which I designed and built specifically so that the tablet would end up at the proper depth relative to the dash bezel).

However, I ran into a few snags. First of all, there's a lot of noise coming out of the amplifier if the tablet is connected to the car's electrical system at the same time that it's audio output is connected to the amplifier. I've ordered an audio ground loop isolator to fix that problem.

The second problem is that the amplifier itself is picking up a lot of noise, such as the heating fan motor, and perhaps some ignition noise. The amplifier is completely unshielded, and gets its ground only through the stereo wiring harness. I need to enclose it in metal, and ground it more thoroughly.

Solved the noise problems ...
 

It's been a few months, and it's time for some updates!

There were two sources of electrical noise in the amplifier mentioned in my previous post. One was differering ground levels between the tablet and the rest of the car, caused by the switching power supply that was powering the tablet. I got around this using a very simple ground isolator (basically a pair of transformers), purchased from Amazon: https://www.amazon.ca/gp/product/B01M1671I0

http://ecomodder.com/forum/attachmen...1&d=1516636725

That got rid of the noise coming from the tablet itself, but had no effect on the noise coming from the ignition, HVAC blower, and fuel pump. To deal with that, I installed a home made BHF (Big Honking Filter), consisting of an inductor and capacitor, as described here: San Antonio Hams

http://ecomodder.com/forum/attachmen...1&d=1516636258

There's still a tiny amount of crackle when the HVAC fan is on low, and also a barely perceptible fuel pump whine. I'll fix these later by adding capacitors to each motor, but it's inaudible over the road and engine noise now.

Installed a kill switch
 

I've been doing some EOC and also turning off the engine at long stops, and until now, have been doing it with the key. The drawbacks to this are twofold:

1. There's always the possibility of overshooting the ACC position, thus locking the steering column.
2. If I want to keep the engine off with the clutch engaged, I have to leave the key in the ACC position. That means no instruments (e.g. speedometer) and no air bags.

A kill switch removes the need to use the key, and allows me to cut off fuel to the engine even when the clutch is engaged without compromising safety.

In my car, there's a single 10A fuse that provides power to the fuel injectors, and only the fuel injectors, so this seemed like an ideal place to wire in a kill switch. I did this using a pair of "Add-a-Circuit" modules, and a high-quality relay with a set of normally-closed (NC) contacts. Here's the schematic/wiring diagram:

http://ecomodder.com/forum/attachmen...1&d=1516637211

The grey boxes with dashed edges are each one "Add-a-Circuit" module. The one shown in lighter grey is plugged into the fuse box in place of the fuel injector (INJ) fuse. The darker grey one is plugged into the primary (A) circuit part of the lighter one, in the opposite direction. 10A fuses are installed into the secondary (B) circuits of both. You can see in the diagram how the current to the injectors flows through both 10A fuses, the NC relay contacts, and the red wires (which are pre-installed on the Add-a-Circuits). Two fuses are of course redundant, and F2 could be replaced with a 20A or 30A unit, since its only purpose is to be a jumper.

A separate 0.5A fuse (shown as 1A in the diagram) provides power to one side of the relay coil. The small fuse is there so if there's a short in the coil circuit (or the wire to terminal 85 comes off and touches something grounded), that fuse will blow instead of F1, which would cut off power to the injectors.

The other side of the coil is connected to a long wire (green) which goes to a pushbutton switch on my centre console beside the shifter. Pushing this switch energizes the relay, opening the NC contacts, and cutting off power to the fuel injectors.

http://ecomodder.com/forum/attachmen...1&d=1516637861

I gave careful thought to the design of the switch so that in the event that it fails, it's likely to fail in a way that the engine can run. If the relay fails to work, the cut-off just won't work. If the coil shorts out, F3 will blow instead of F1. There is still the possibility of course of the relay itself getting stuck open, or double the possibility of a nuisance blow because both F1 and F2 are in the circuit. However, if anything does fail, I just need to pop the hood, open the fuse box, pull the Add-a-Circuit out of the INJ fuse socket, and put a fuse back in its place.

Here's a pic showing the actual kill switch (my wife calls it a "Kill Bill" switch, because it's yellow like Uma Therman's outfit in "Kill Bill").

http://ecomodder.com/forum/attachmen...1&d=1516721567

I also remembered two additional advantages of using a kill switch instead of the key:

1. If I'm signalling and turn off the key, the signal stops until I turn it back to Run.

2. Likewise, the DRLs turn off while the key is turned to Acc, probably making other drivers think I'm flashing my lights at them.

Nice work on the kill switch! I'm still trying to source a reasonably priced NC momentary switch for doing a kill switch in my Ion... Where can I find one? Hadn't found a good one yet...

Unless you're looking for something pretty, I recommend going with a nice snap action / limit switch. You can get them for about $1.50 on digikey. If you're looking for something pretty... it'll be a few bucks.

This one of the ones I use in my 3d printed shift knobs. It can be wired NC or NO.

https://www.digikey.com/product-deta...SW500-ND/83270

https://media.digikey.com/photos/Omr...%20D2F-01F.jpg

Thanks!

The switch I used is NO, and it is used to energize a relay with NC contacts. I didn't want to run the fuel injector supply voltage all the way from the under-hood fuse block to the centre console and back due to power losses and more points of disabling failure (e.g. the wire breaking or coming off the switch). Also, in my experience, an NC switch is much more likely to fail open than an NC relay.

I did choose a fairly robust switch though, since it has to survive in the harsh environment of a car, and I didn't want the switch to become non-functional, even if it doesn't disable the car by failing:

https://media.digikey.com/photos/E-S...S64016_sml.jpg
https://www.digikey.ca/products/en?keywords=EG4724-ND

It's dust proof, water resistant, and its electrical life is rated at 200,000 cycles at 2A. It should last for its full rated 1,000,000 mechanical cycles in my application since it's only switching 0.25A.

Eco Mod Versus Unfortunate Feline
 

While driving home a few weeks ago, a cat ran across the road literally in the last few milliseconds. It darted out of the grass, across the shoulder, and right in front of the passenger side of my car. There was simply no way to avoid it, and as I looked in the rearview mirror, I saw a deceased cat and bits of plastic tumbling along the road.

Of course as a cat lover, I feel bad about the cat (and its owners, although given where I was driving, it was likely an unloved barn cat), but this is the Ecomodder forum, not the general Internet (which is primarily for and about cats), so on with the damage assessment...

I noticed immediately that my right side air dam extension was missing a cat-sized chunk. I neglected to take a picture while it was still on the car, but suffice it to say that the one piece extension was now two pieces.

I also noticed that there was a big crack in my grill block, with a small piece missing, and one of the metal mounting brackets dislodged. I'm not positive the cat caused this, but I think so, due to the flexing of the bumper.

But the worst thing was that my radiator intake-side shroud was broken. I noticed that the factory air dam was loose one side, but then discovered it was still firmly attached to the shroud, and that the shroud had a crack all the way up to just under the hood. It's possible that my air dam extensions prevented the factory air dam from bending backwards (it's flexible), and instead transferred the impact into the shroud.

I elected to just do quick patch repairs to get the eco mods back on the road, and will rethink the entire thing in the summer, perhaps using more flexible materials than the ABS I've been using.

This picture was taken after I patched up the shroud, using an aluminum plate, stainless steel screws, and outdoor-grade cable ties. This area is immediately behind the passenger side headlight (I removed both the headlight unit and its mounting bracket to get at the broken shroud):

http://ecomodder.com/forum/attachmen...1&d=1519948212

I patched the damage to the grill block using a piece of the same ABS, held in place with screws and ABS cement. It looks a bit rough, but it actually looks better in real life (I had to crank up the low level contrast to make the repair visible in the picture):

http://ecomodder.com/forum/attachmen...1&d=1519948463

Finally, I made a new air dam extension (and one for the other side too, since it had a small crack in it). Rather than using ABS, I used polypropylene from a boot tray. I'm hoping this will be slightly more flexible, but I'll probably make new ones in the summer out of vinyl (PVC):

http://ecomodder.com/forum/attachmen...1&d=1519948623

A Milestone!
 

You should take some heavy oil and pour some into the subframe on the left side, The right side is automatically done during oil changes. I think that's why the right side doesn't rust out. Impressive odometer, oh wait its km.

Neither side is rusty. The car is sprayed every year.

First a Kill Switch ... Now a Revive Switch
 

As my hyperkilometring evolves, I've found I use my kill switch more and more. When using it while rolling, I've usually restarted by letting out the clutch, but it's very hard to do this smoothly, since of course I can't match engine RPM to gearbox RPM when the engine isn't running yet. I think if you do this smoothly, it's hard on the clutch, and if you do it roughly, it's hard on the engine, transmission, and mounts. Thus, I've changed to restarting using the key.

The problem is, this is kind of awkward when in motion, so I came up with the idea of installing a "revive switch". It basically duplicates the process that turning the key to START does, but with just a button next to the kill switch. Here's the schematic of what I've done, added to a stretched diagram from the service manual:

https://ecomodder.com/forum/attachme...1&d=1532222030

There are two identical SPDT relays, with their coils wired in parallel, and powered by the RUN-only wire from the ignition switch. A pushbutton to ground is used to energize the relays. [Aside: The diodes are part of the relays. My kill switch relay didn't have one, and always produced a loud pop in the sound system when the button was released. Adding a diode completely eliminated that, so I ordered relays with diodes already installed this time.]

When the really is not energized, the RUN-only wire (orange) goes through the normally-closed contacts of the first relay, and from there on to the RUN-only section of the fuse box. Likewise, the RUN/ACC wire (brown) goes through the normally-closed contacts of the second relay, and then on to the fuse box. Both of these wires were previously connected directly to the fuse box.

When the "revive" button is pushed and the relay is energized, the power from the RUN-only wire is redirected to the starter circuit instead, and the RUN-only part of the fuse box no longer gets power (as it shouldn't during starting). Likewise, the RUN/ACC part also no longer gets power (as it also shouldn't).

As far as the rest of the car's electrical system sees things, exactly the same thing has just happened as if I'd turned the key from RUN to START.

Here's how it looks under the dash. I fashioned a small mounting plate for the relays out of 1/8" aircraft plywood, and bolted it to a metal rail close to the wiring harness:

https://ecomodder.com/forum/attachme...1&d=1532223206

Here you can see the two buttons. The yellow one was formerly my kill switch, but is now the revive switch. The more aptly coloured red one is the kill switch now:

https://ecomodder.com/forum/attachme...1&d=1532223206

I did run into one snag... The schematic I had, from what appears to be a scanned version of the service manual, had the brown and pink wires from the the ignition switch swapped. So pressing the button disconnected stuff that was supposed to remain powered during START (like the BCM), and did not disconnect stuff that should have been (like the audio system). The engine cranked, but wouldn't start.

At first I thought I'd run afoul of the PassKey II security system, but after much Googling and pondering the symptoms, I came to the conclusion that this wasn't the case. I went back and monitored the voltage on each wire out of the switch in each switch position and discovered the error in the wiring diagram. After some more Googling, I found another diagram on SaturnFans.com (in black and white, but with the colours labelled), that had them indicated correctly. After rewiring, everything worked. Unfortunately I now have an unnecessary splice in the pink wire.

Correctly bump starting shouldn't be hard on the clutch. It takes 1/10th of a second to spool up around 40kg of mass inside a small engine. It takes about a second of slip to get a 1000kg car moving from a stand still. The wear rates aren't even remotely comparable.

I always did like a double clutch action. You learn just how far to let the clutch out to get it turning. Do it fast clutch out and back in, engine get up in rpm and release clutch. Some cars idle up fast initially and at the slower speed it can match up. I did it for years in my SC1.

The difference is in the speed delta. To get the car moving, you're starting with an 800 or so RPM/difference (engine speed 800 RPM, driveline speed 0). To restart the engine at speed, the difference is around 2000 RPM (engine speed 0, driveline speed 2000). So that 1/10th of a second is probably about equivalent to 1/2 a second of getting a car moving.

The RPM delta doesn't matter. You only need to transfer X newtons to get an engine cranking. During a bump start, the greater the speed differential, the shorter the required contact. Same energy transfer= same amount of wear.

You can try this (in someone else's car of course). Sit on a hill, hold the car on the clutch at idle. Increase RPM. The car doesn't move because regardless of RPM, you're only transferring the same number of newtons.

Slip time is what wears out your clutch, not RPM.

The reason people think it's RPM is because from a standing start engine and road speed will take longer to match if you release the clutch at higher revs.

Besides which, I can bump start my car from around walking speed in 3rd. That's about a 200rpm delta.