Meet Mr. Corolla

[tcaud]

https://imgur.com/gallery/5u43T (warning: pics are detailed and bandwidth intensive)

I'd like to make him more fuel efficient and possibly greener.

- 2002 model
- 309k miles
- 30mpg avg per tank, about 80% city/20% highway
- Uses 5w20 synthetic oil and gets treated with additives by Midas
- body dents on right fender and back bumper, with a couple other minor dents around/on the doors. Also some rust issues along the wheel well. Not too worried about this because I consider him a beater. When time is right I'll get a full electric. In the meantime, I just paint over it. :P Do the dents
- The front wheels are missing hubcaps and the back wheel hubcaps have cracks. All the wheels are rusty (one is apparently bent by a margin) and I mean to replace them soon. I hear wheel weight plays a role in efficiency... how much? I think I can get replacement OEM hubcaps for cheap... would those be preferred or are the less stylish/grooved disc-like ones more aerodynamic/efficient?
- The back trunk is kept empty and the spare has been removed.

Hypermiling seems impossible in the suburbs of Cincinnati, where the roads are hilly and stop signs are encountered every quarter mile. I accelerate slow and try to coast to red lights. Looking for statistical gains thru mods, not changes in driving style. Also would love to cut his emissions. I use him for work so reduced driving isn't an option.

[tcaud]

I've been thinking about a front air dam, however this car already seems to have a spoiler below the grill. Also as regards a grill block, the car gets hot quickly... I have no problems at all in the winter keeping it warm, and I have to run the AC on at least half in the summer even on mild days to keep from sweltering in the dry engine runoff. I was looking through the wind charts thread and noticed that the 8th gen Corolla series has one of the least aerodynamic designs. But it has that precisely to provide for its beefy trunk. It's a great all-purpose vehicle.

I figure it could benefit potentially from a hybridization, which might get it 40-45 mpg. Would like to see this attempted because I don't think most will ever go for the hatchback design over the sedan on account of the trunk space. Perhaps it might do even better than a hatchback on account of its low stock weight (2500lbs) and high horsepower (140).

[freebeard]

Post more. ...and throw away those other two hubcaps.

[tcaud]

On closer inspection I think this car could do well with a front dam. The undercarriage hangs about two inches below the grill, so there's definitely room for improvement there. I'm going to be asking around on the Corolla forums to solicit opinion. Also I read up on the Porche 914 aero thread... particularly the diagrams of cars with different aero configurations. This corolla pretty much has a 90 degree slanted back windshield, which according to the diagram improves economy, but it's not clear from said diagram that it would improve with a rear spoiler. I also mean to increase the tire pressure to 36psi from the stock 30 (max sidewall on my Hankook Optimos is 44).

I wonder if it would be possible, with a belly pan, front dam, back wheel skirts, increased psi, disc wheel covers and rear fin to increase avg mpg to 40 from the stock 30. Messing with the mirrors is completely out of the question, though.

[Daschicken]

Want to reduce emissions? Lots of bad stuff happens on cold startup, an engine block heater can help that greatly. Letting off throttle more slowly(avoid sudden high vaccum) helps reduce unburned hydrocarbons. Make sure your EGR system is working properly and not clogged, that will reduce NOx(lower combustion temps) and reduce CO2(better fuel economy). Clean out the intake if it hasn't been done before. Make sure the spark plugs are serviceable.

You said the fenders were dented, and the car has over 300K miles on it, so clearly resale value isn't very high. You could cut the fenders right on the top edge of the wheel well and fold them in, effectively radiusing them like a 1st gen honda insight. Of course, this won't do much if you don't see high speeds often.

Toyotas often have overboosted power steering, so more gains for you there. I disabled the power steering in my 3300 lb V6 accord, its doable, but not for the weak-armed. Since you do mostly city driving, accelerating(higher rpms) and turning(actually uses the P/S), you should gain more from a P/S delete than I did. My delete was worth a little less than 1%, almost unnoticeable fuel economy wise. However, it did make the car accelerate noticeably quicker. And if you don't like light steering, well...you won't have to worry about that anymore.

I just recently went from 23.5 lb 17" rims with 25-26 lb 215/50/17 tires down to 16 lb 16" rims with 20 lb 205/60/16 tires. That's 12 pounds PER WHEEL! It resulted in noticeably quicker acceleration, likely meaning less fuel to get up to speed, and less momentum going to waste when it is time to brake. If you do lots of city driving with plenty of stop signs, that would be a great option for you. Mini coopers have VERY lightweight 15" alloy rims(12-15 lbs!), make sure your bolt pattern (4x100mm?) matches up with those wheels and see if someone is willing to part with a cosmetically damaged pair.

I'm just going to tell you right now that you are going to be disappointed in the gains that mods alone are worth without changing your driving style. Mods and driving style help work together and may offer a benefit larger than the sum of both.

As far as accelerating: If you have a free road ahead, try to accelerate at a rate that gets you to AT LEAST 2500 rpm. Moderate acceleration is actually beneficial for economy, but acceleration technique in general doesn't make much impact on mpg. If there is traffic ahead, and behind, you could accelerate slower, at a rate that doesn't make the people behind you angry, but also doesn't mean much momentum is wasted when it is time to slow down.

[Ecky]

I'd like to throw out there that "hybridization" isn't something that can work as a bolt-on. The main advantages a Prius has over a Corolla, which runs a very similar ICE, is that the Prius is able to run the significantly more efficient Atkinson cycle, but which lowers torque at low RPM. The added electric torque makes up for this and allows for keeping the engine RPM down (often lower than the Corolla), and shutting the engine off at stop lights and in traffic creep helps significantly in city driving. Regenerative braking doesn't usually account for much.

If you just add an electric motor and battery to an existing drivetrain, you'll likely get single-digit percent improvements in economy. To get the real benefits a hybrid has:

1) You can emulate auto-stop by key-off at traffic lights and possibly engine-off coasting toward redlights and stop signs.

2) It's likely possible to run the Atkinson cycle in your Corolla. I'm not sure if Prius cams would fit, but you could likely have your cams reground or new cams made that convert to Atkinson cycle, plus a tune. In exchange for losing some power, you'll gain real, measurable economy. Probably not cost effective though.

3) Regearing can help in any vehicle, though you'll mostly see improvements on the highway. A taller top gear can easily be worth a double digit percent improvement.

If you're looking for quick, easy and cheap things that help in stop and go, look at cutting down on weight, especially at the wheels. If you can get a set of lightweight junkyard alloys, they might provide a measurable improvement. Also consider adding a kill switch.

[tcaud]

I try to stay in the sweet spot range, which I hear is between 35-55 for most vehicles. I'm not totally sure what it is for Corollas though... they have reputations as highway cruisers and I hear economy is good even above 60mph. I do a lot of coasting and I'm working on avoiding complete stops when approaching red lights. I don't think 8th gen Corolla automatics are suited to a lot of use of neutral... on the Corolla forums people say they use neutral for no reason other than for engine-breaking. So (automatic) Corollas just may not be suited to hypermiling. I do use 2nd gear though for getting up steep hills... I suspect that does actually help with the gas because I notice the needle doesn't start falling when going steep hills in 2nd, the way it does when it changes gear and pushes itself to make it up in drive. Pulse and glide doesn't seem very effective with this car... it tends to slow down rapidly as it approaches the tops of hills here, requiring a lot of extra gas. May just be the area and its steep, rolling roads (Cincinnati has lots of those). I seem to do better by just doing constant acceleration with a slight increase going up. I looked through the entire list of hypermiling techniques here and next to none of them would be tolerated here, or even safe (maybe in rural areas, though).

EDIT: OK I hit the posting limit so you can see the pics now.

[Grant-53]

My Corolla was a '95 with a 5 speed. I used the aluminum rims from an older Ford Escort GT. Since you are not planning an engine overhaul, use aerodynamic improvements. Fixing the rust spots reduces skin friction a bit. The air dam could be lower in front of the tires and a lip over the rear window would help in addition to the mods previously mentioned. If you have access to a technical library check articles by W H Hucho and Joseph Katz among others. Look at the photos of the Probe V, Citation IV, and Mercedes Benz C-111 Mk. 3 prototypes. The wheel strakes on the Probe could be made from foam.

[tcaud]

Atkinson sounds interesting but also unaffordable. It comes down to the fact that the car is weathered... rusted as you can see in the photos. The rust is particularly bad along the wheels and the side trims, even through in some places (large chips of the wheel well have broken off). But the real kicker is the damage to the back, which would require replacing more than half the body paneling. To get this car where it would need to be for keeping long term... $5000 probably.

I looked at the wheel wells and noticed that the back tires protrude from them. Unless I installed well rims then it wouldn't be possible to cover them. Finding well rims for this model is a challenge in itself.

Looking at the front bumper, it's not clear at all where a dam would hang from. There is a grill in the middle and the area below it is thin, hollow, and angular... drill holes would probably destroy it. It's as though the designers went out of their way to make the design as unfriendly for FE mods as possible. I'd have to replace it with a thicker base and install a dam to the replacement, probably.

Regarding the suggestion of a spoiler above the rear window, I heard those actually decrease economy. Are you sure it would work? Also
@Freebeard you told me to discard the cracked hubcaps. Why do you recommend this?

@EDIT: I have an idea. Considering I have to display the license plate anyway, I can use the plate screw holes and make the dam very high up on the front bumper (starting at the middle). That will give me plenty of space. I could drill a couple holes on the sides and hold it that way. Still not sure what to do about the wheel skirts though, or if that's even a good idea if it can cause heat buildup around the break system...

[freebeard]

@Freebeard you told me to discard the cracked hubcaps. Why do you recommend this?

I hate hubcaps?

My friends have a Prius that lost one hubcap. It turns out Prii have black powder-coated Y-spoke mag wheels under the fake 5-spoke plastic hubcaps. The car would look much better with the other three removed. They won't do it because it wouldn't look show-room fresh, but they won't spend the money for a fourth fake 5-spoke plastic hubcap.

well rims

Are we talking about 'wide-body' arches? It doesn't show in the picture but the car in my avatar had fender extensions (before I cut the front half of the front fender off and lost 5mph of top speed) to clear F60-15 tires. I went to a sheet metal shop and ordered a circular sector (a curved strip) 3" wide with a radius 1.5 times the wheel/tire diameter.

Bent into a circular conic section for installation:


https://en.wikipedia.org/wiki/Conic_section