The Dutch 100MPG(?) Peugeot 106
 

Hi All,

Years ago I stumbled upon this website and the idea of eco tuning a car stuck. Together with a friend, we finally found a good reason to do it. For a major Dutch magazine, we're investigating how much more efficient a current petrol car can be when we do some compromises to design and comfort.

The original car is a Peugeot 106 1.1 with 60 hp and a factory consumption of about 1l per 16.5 km (around 39MPG). We want to improve this with at least 100%, so around 80 MPG, but we're hoping 100 MPG might be possible to.

So far, we've stripped about 55 kg (not much effect) and added that weight with a durable tail section. Nice detail: we can still use the tailgate, the entire tail section can flip open. The rear wheel covers can be removed. All the parts are hand made in steel and aluminium. The plastic rear panel is temporarily, we want to make that out of aluminium as well, with nicer led lights.

https://i.imgur.com/SHsH3XS.jpg

https://i.imgur.com/bU9PPVp.jpg

Next on the list is making a new front bumper out of aluminium and covering as much of the underside as possible. We also have some Renault Twizy tires and we want to shape the front quarter panels like the Peugeot Vera Concept from the early 80s. No idea if it really helps, but it looks cool.

https://topworldauto.com/pics/Peugeo...vera-02-01.jpg

Of course we want to do better than this car...

If anyone has some great tips for further improving the economy..? Let me know!

Nice workmanship! :thumbup:

Looks awesome :). I wish such boattails would be legal on cars.
Another gain possibilty would be to work on a powertrain efficiency. I drove a 1.1 106 long time ago and the revs are quite high on freeway. With such reduced aerodynamic drag if you want to enjoy the result you'll have at least to reconsider gearing.

Trya a warm air intake

You could add a rounded nose to lower the stagnation point at the front of the car with an incorporated adjustable grill inlet to control the amount of cooling air flowing through the radiator. Position the opening to the grill inlet below the stagnation point on the rounded nose. Could also install front wheel covers and a wind deflector for the windshield wipers. Is there any reason you couldn't extend the boat tail to a smaller cutoff point?

We've thought about that, but a computional fluid dynamics model suggests that a further extension has only minimal gains. So Wunibald Kamm was right :D

https://i.imgur.com/dy9SuTh.jpg

https://i.imgur.com/VQtOPmE.jpg

It also shows that further improvements mainly come from the front and the transistion from windscreen to roof. That last one might be a tricky one, but the right shape of 'wind screen wiper shield' might help to shape the flow in such a way that it creates a more efficient flow over the car.

Hi,
Nice work!
Any mpg results so far?
Have you got any pics of the facial of the car!

No, unfortunately, due to the extensive lowering of the car (about 3 cm's at front, about 5 in the back), one of the driveshafts is nearing end of life. So that needs to be replaced first. Mind that this is a hobby project, it's not our daily driver, so we'll work on this in our spare time.

Another thing we've done so far: making camera mirrors based on 20 dollar rear view camera's from AliExpress. The housing is made of the interior part of the mirror housing and some plywood an lots of filler.

https://i.imgur.com/SAHgDFv.jpg

https://i.imgur.com/fkYghcw.jpg

Good thing about these camera's is that you can choose weather you want a normal or mirrored view. That last option makes looking at the monitors more natural.

That thing looks amazing. The sheet metal is just glorious, making it an operable hatch is even better.

That's an interesting project to say the least. When it comes to the boat-tail, have you never considered to make it out of some plexiglass or other plastic in order to improve rear visibility and maybe getting the taillights in a position that would allow a lower drag?

Subscribed! I love your boat tail.

The Honda Insight could achieve 100mpg (US) from the factory with a little extra air in the tires. You could look for some of the design elements used in that car perhaps? I'm happy to take some pictures or describe those I'm aware of.

I changed the engine in mine from the thrifty 1.0L to a power-oriented 2.4, and the best economy I've seen since then has been around 65mpg cruising, under the same conditions the old engine was showing 100mpg - cruising at no greater than 50mph.

It seems the new engine isn't (much) less efficient at producing power, but that it has larger parasitic losses. For instance, it uses a lossy alternator instead of a highly efficient DC-DC converter, it has a bigger water pump, bigger oil pump, the serpentine belt looks to be a little over twice as large, another cylinder's worth of frictional parts, a second camshaft, etc. Because of these, it doesn't seem to scale down as well - there's a larger fixed amount of fuel consumed just running the engine to do the same amount of work.

Where the old engine could produce (let's say) 20hp, the new one uses around 33% more fuel. However, the new engine can produce ~65hp at close to the same efficiency with my current gearing. Meaning, with pulse and glide (accelerating for periods with 65hp then shutting the engine off and coasting for a bit, rinse and repeat) I expect I could get very near that same 100mpg. It's possible I could get close to 100mpg with the new engine if I had MUCH taller gearing (all of those lossy parts would be spinning proportionally slower) but it simply wasn't possible to fit gears large enough in the gearbox.

All of this is to say, you may be able to squeeze a little more out of your engine with taller gearing and a set of underdrive pulleys, to slow down those lossy accessories. It's not a bad place to look for gains after you've already picked the low hanging fruit from rolling resistance and aerodynamic drag.

Thanks for the help and info!

Small update:

we've completed the front of the car as well, a nice airdam with the front of the undersection closed as well. We've also finalised our camera mirrors, the car looks so much better without those big black mirrors. Tueseday it will get some TLC on the technical side and then we can finally do some proper testing. Keep you updated!

https://i.imgur.com/cAqcE4F.jpg

*not visible, but we made the rear panel of the boat tail out of aluminium as well (previously white plastic, see photo on first page) and made the trailer rear lights sunken, so no more blocky structures at the back.

There we go, pic of the updated rear as well!

https://i.imgur.com/8J2J6Ay.jpg

Besides the camera mirrors, all the adjustments seem to be within the limits of the law and re-inspection by local authorities is not needed. That means we can probably get it trough MOT easily =)

Is that tow loop accessible with the air dam?
Not that i would question 106's reliability but still :D

Have to say, very clean&smooth execution on those ecomods :thumbup:

Nice. Subscribed.

Very fun project, and nice workmanship!



How will you be measuring fuel use to determine the difference?


Have you already done a "before" test to get the baseline? Be sure to note weather conditions - ambient temperature has a significant effect on efficiency on its own.

Paint them red and put something like a 107 or 108 sticker on the back. People will think it is a different model :)

further extension
 

Kamm's best car,the K-5,at Cd 0.23,had an aft-body length equal to 1.63-X the actual body height (no ground clearance included).He did recommend an inflatable boat-tail stinger which would extend the aft-body out to 2.03- X,chopped off like all 'K' forms,which would deliver Cd 0.1909.Extending the tail all the way to its termination point,at 2.72-X yielded Cd 0.1742.
Sure do like what you're doing.:thumbup:

I'm currently having computer issues and have resorted to using my cell phone.

1. The underside of the boatail does NOT look finished and closed off, is this correct?

2. Any plans for a belly pan?

3. I would also like to see the underside of the front chin spoiler, is there a partial pan there?

Overall a fantastic project, rivets and all.

Thanks, the entire underside of the boattail is closed, it's just a bit recessed to ensure a proper connection to the underside of the car. The front bumper is closed at the underside as well, but there is not (yet) an entire belly pan.

The car is in storage at the moment due to corona... :/

I started looking at ways to do my car months ago, and found little information.

Was about to do some serious number crunching when I came by this thread

106 friend!!!

Any chance, you could show us all how you constructed the tail? Did you keep the standard hatch and cut the inside out to leave a frame to attach the sheet metal too - giving you a hinge and a latch to hold it? I was going to do my tail floor a bit steeper providing I can keep the flow from underneath attached.

Are your wheels discs just held in place by a screw in the centre, the standard hub cap is beneath this?

I'm using the 1.5 Diesel engine in mine. It manages 55mpg (real) 45mpg (US) and I give it a hard time. The best I ever got from it was 84mpg imp but I've only ever managed that once.

This is amazing! The craftsmanship on the modifications is wonderful, keep up the great work!

So, finally an update on the Peugeot 106.

We wanted to have all the mods complete before end of MOT, but the first Corona-wave made us miss that deadline. Therefor we had to MOT the car. Although we thought we didn't do anything illigal (besides the camera mirrors, but we can replace those in a few minutes), we were still a bit worried. In the end, we only had to put some rubber on the sharp edges of the aluminum aero tail. So now the car is road legal for another year.

But we weren't satisfied with the results we were getting. We could only achieve around 1 liter per 25 km (+/- 59 MPG), whatever we tried. But we've found the solution!

We originally chose for a late model 106 because of multipoint injection, so we could make our own cylinder shutdown. We never thought of it again because of the misconception that it would be to complex. For around 30 bucks, we bought some connectors, wires and a switch, so we can interrupt the positive wires going to the injectors of cylinders 1 and 4. At idle, we can also switch them back, but at speed they won't switch back on. Something with the ECU probably, because when we turn the key and switch it back on, they will work. So we're probably going to make a switch to cut off the power of the ecu while coasting as well.

More importantly, the car drives amazingly well on only two cilinders. It's not powerfull enough to have proper acceleration, but it's more then sufficient to retain a cruising speed of 45-50 mph. And fuel economy was improved massively, we're now getting 1 liter per 35 km (82 MPG) and we think we can do even better on a route with less height differences. We think we might be able to push it to 1 l/40km (94 MPG) with the camera's mirrors on, and a flat and boring route with a cruising speed of around 45 mph.

https://i.imgur.com/4SN5gfy.jpg

https://i.imgur.com/wSjROIz.jpg

Also note the self fabricated windscreen wipers with aero blades that sit much lower the the original ones, barely obstructing the wind flow anymore. (we've ditched the spring, so you can only replace wipers by taking the entire wiper arm off).

We made a steel frame welded to the original tail gate of the car:

https://i.imgur.com/HXVT3Cu.png

https://i.imgur.com/9KbPcWQ.jpg

We made cuts in the steel bars every 5 to 10 cm's with a grinder and then welded them back together to get the desired curve. We then made paper templates of the aluminium panels, that we formed on the car using metal working hamers and spanners:

https://i.imgur.com/NhBN3bE.jpg

So we nailed the panels to the frame while holding them tensioned and that worked surprisingly well. It turned out better the we expected.

We welded a bracket to the original steelies:

https://i.imgur.com/WA6jrla.png

The we made a hole with thread in the brackets, to mount the aluminum wheel covers with a single bolt.

What a cool project and car to choose for this kind of modification.

Revisiting this forum has definitely fired back up the urge to get back to ecomodding (just as soon as I've finished ecomodding my new home).

Hats off to you, sir!

I vote for Peugeot 007 :)

I think this thread can be moved to succes stories...

Today we drove 459 km's and we used only 12.12 liters of petrol. That's 2,64 l / 100 km or 89.08 US MPG! It was a route with mainly highways and we drove 75 km/h all the time on 2 cylinders. So not entirely representive for everyday driving but we're very pleased with the results. Mission acomplished. Thanks for the inspiration Eco Modders!

More info later.

Patiently awaiting further updates.

I’m gonna ask, is it not highly dangerous to be running half your cylinders? Many people say this a risky thing to do. The mileage increase is crazy, though.

Sure there might be some drawbacks under specific conditions. On a sidenote, when I was in my early teens, I considered it could be reasonable to replace a 4-cyl 1.0L car engine with a 500cc parallel-twin out of some motorcycle with a similar power rating - little did I notice how the substantially different power and torque curves and peak RPM bands would affect overall performance.

Congrats, Dizono. Looking forward to the article/report!

I read that you got the car through the APK (dutch for general periodical inspection), but was there any hassle over the modifications done? Do you think you will be sent to the RDW (the guys that do more stringent type inspections) like Wim Schermen with his fully enclosed motorcycle. Did you get pulled over?
Not knowing this is what is holding me back the most from modding my 2001 renault kangoo 1.6.

Just loving your effort on the 106 and the cylinder delete is just really cool. Does the block mind the differential heating?
Otherwise an awesome way of increasing the BSFC.

Groetjes,
Max

Are you more concerned about aerodynamic or engine mods?

Hey Criple rooster and everyone else,
Since a have a car with a very boxy rear end, most fuel savings will be had by improving aerodynamics. Adding a partial boat tail (and in doing so some cargo volume) seems very apealing to me. At cruise without mods at 100kph my intake air pressure is about 45% of atmosphere, thus if i improve aerodynamics just a bit i could run just 2 cylinders at 80 % atm. This would net me some fuel savings again (maybe 5 % - 10 %?) by reducing pumping losses.
What do you think?
Head gasket problems, fuel trim going rich, catalytic converter overheating?

If you add cargo volume make is a separate compartment. Don't delete the hatch, it's added structural rigidity. A box that is exposed when you lift the hatch would work.

Nice project, but I'd think it started out with the wrong car -as in not very efficient to start with.

Surprised you get it through MOT so easily in NL


Groeten uit Vlaanderen

Just as euromodder stated.
I think my main concern in this thread is the MOT.
I almost exclusively use the car for hauling things. A little extension of the cargo bay would be nice. A smaller car would not be an option for me. This car 3 m3 of cargo volume and is conparatively cheap in road tax. It weighs 1080kg (in the Netherlands road tax goes by weight class).

Groetjes uit NL

I remember seeing a Citroën Jumper campervan with some sort of "backpack" extention in my hometown once.

https://i.imgur.com/bU9PPVp.jpg

It needs at least a trailer hitch box. Best would be a pickup bed with a diffuser with fences in the bottom.

English text via link in a few messages. Can't post links yet....

4 to go....