Hi all, new here

[Photonfanatic]

Just got my first good gas mileage getting car. A 2009 toyota yaris. I'm quite impressed with its miserly 33Mpg city, and 38MPG highway fuel mileage. Pretty good for a non hybrid, straight gasoline car if I do say so. I am really impressed with the amount of interior space that you get, with that kind of gas mileage. To me, the car really is a feat of engineering.

But anyway, I wanted to see if there are any typical mods to the Yaris, that are well known. Ecomods, that is. I was reading some other page on this site that attempts to list most of the common mileage mods. So I'm pretty sure I'm going to lower the car about an inch in the front, and perhaps 1.25 inches in the back. Should give it the look I want since it sits a little higher in the back, and help with mileage. But what else? I was also thinking of those E3 spark plugs, and maybe a less restrictive exhaust system IF its not going to sound like a weed eater like the rest of those 4cyl hot rods. Its starting to seem like you can get a good flowing exhaust these days without too much noise. Flowmaster is making some kind of new muffler called the hushpower that is supposed to be quiet but flow as well as straight pipe would. Is there anything else that I should know about for the Yaris?

[brucepick]

Welcome to ecomodder! Hope you do real well with it, all around.

I probably should say, there are so many ways you can improve your fuel economy, it almost doesn't matter where you start. I think that's one of the reasons people have success with this, and so stay in it and keep improving.

I have to say, probably the single most important mod is adjusting the "nut behind the wheel". I eventually changed just about every driving habit and convention I had, including road speed for any given piece of road, acceleration, how I approach lights and other stopping or slowdown situations, and more.

Sorry I don't drive a Yaris so I don't have specifics for that car. I'm sure others will chime in with some specifics once they come back to life after New Year's Day. Which version do you have? 5-spd? 3-4-or 5-door?

Lowering can help the car's aero behavior. But I think in terms of gain per dollar spent, there's plenty you can do for less money that will likely give more gain. I certainly wouldn't worry much about exhaust. Exhaust does matter seriously when you're trying to get increased power from the engine, for 1/4 mile times or for um, a stop light derby. More power means more exhaust going out, so you need a better flowing system. Driving for mpg, you'll likely spend most of your time running at 25% - 35% of red line rpms, and those low rpms will mostly at something like 25% throttle. I'm guessing the existing pipes can handle what you'll give them. In fact some have experimented with restricting the stock exhaust slightly to ensure back pressure and good exhaust scavenging at lower power levels.

I think this is the list you saw here, of most common + useful mods for fuel economy. A sticky at the top of the "Ecomodding Central" subforum. http://ecomodder.com/forum/showthrea...-mpg-5170.html

Anyway, where's the nice low hanging fruit for eco-mods?? See the master list above for suggestions. Definitely put your tire pressure up as high as you dare. Quick, easy, and low/no cost. I'd suggest whatever the tire imprint shows as a starting point. When you need new tires, definitely get low rolling resistance ones (LRR). Grill block is near the top of most peoples' lists. I pay close attention to my digital coolant temp gauge when I run my grill block. I'm conservative on that, and don't like it going above 190-195 ºF. My grill block is lengths of foam pipe insulation duct-taped together to make blocks that fit my car's slots. I've seen prettier but adding/removing sections is super easy, and the cost is almost literally pocket change.

Flat wheel covers. Warm air intake can help, but the designs vary with what car you're modding. Cold air intake is nice for power increase, probably not your game here. Belly pan is nice. The Yaris bottom might be pretty smooth but most cars still have open areas under the engine bay that can benefit from getting smoothed over.

A good fuel economy gauge. An MPGuino gauge refreshes the screen 2x/second and reads out in hundredths, for both miles and gallons. ScanGauge is not as accurate - it derives mpg from air flow sensor and speedo data, but it will also show useful info such as engine temp and system voltage. For info, see the "Instrumentation" forum here, and the "MPGuino" subforum visible at the top of it's page.

Whew. Hope I didn't scare you off! As I wrote up top, there are so many ways to improve mpg, you can start pretty much anywhere.

Good luck with it!! Come back with more questions, and let us know how it goes too.

[Photonfanatic]

Thanks for the welcome and the reply. But yeah me personally, I'd be a little wary of blocking the grill or even airing up the tires too much. With the tires, of course I'm sure you know that its going to make them wear faster, in a certain pattern. Then you have to ask yourself, where is the point of diminishing returns? Cause if you have to buy new tires a lot sooner, (which are of course super expensive) then you're not really saving all that much money.

[Photonfanatic]

Yeah I saw this page:



Looks like a lot of good info in there. Now I just gotta convince the wife to let me start doing this stuff to our car. Oh and its a 4 door sedan, automatic. Over at the yaris forums, the general consensus seems to be that the 4 door sedans get better mileage than the hatchbacks due to lighter weight. But the standards can get roughly 1MPG better than the automatics.

I also own a 1987 Chevy Silverado that one day, I'll be swapping the 5.7L V8 for the much newer and much more fuel efficient 5.3L LS V8. Old truck will need a new engine someday anyway, and this swap has been known to yield all the way up to 8 miles per gallon. My other ride is a 1994 Mustang GT, which of course will only see power mods that if they help MPG, well that's good I guess. LOL Although I can say, that I don't want any of the power mods to really hurt MPG either. It gets low enough as it is, at 18MPG. Its nice to know that when I lower it though, I'm actually helping its fuel efficiency.

But those two vehicles can really only go so far. The yaris on the other hand, can go to new heights.

[California98Civic]

Welcome to ecomodder. Look at what "redyaris" is doing on this site. An auto trans has limits, but it can be improved. His aero mods would be a start. But you can start right away with raised tire pressure and slower highway driving. You will see good gains from those and you won't need to convince your wife to do them. Get an UltraGauge or a ScanGauge. Just watching the numbers will teach you what works for boosting them. Good luck!

[brucepick]

All other things being equal (which of course they never are), sedans will usually get better fuel economy than hatchbacks or wagons due to aerodynamics. The larger rear "face" of the hatchback gives a larger wake with resulting higher overall drag. The extra steel and glass hurt some, but the added drag hurts more.

My tires last longer now, at higher pressures, than they used to when I went by the book. They were always worn on the outer edges with deep tread in the middle. Going by the book resulted in classic examples of underinflation. I finally learned my lesson on that.

There's an awful lot of very old information out there re. tire pressures, rooted in the old bias ply tire days, before belted radials.

Please have a look here re. tire pressures.
Driving Under Pressure (full article) - CleanMPG Forums

(photo from the article)

[Photonfanatic]

Thanks for the replies. Hmm in the article they say

"Much better tire wear results from maintaining proper pressure. Tires with lower pressure will wear off the outside of the tread faster from the deflection of the tire during cornering, and the tires will heat up more from increased road friction. This is one of the factors that caused the failure of a certain brand of tires on Ford Explorers some years ago. In 1999 the San Jose Police Department realized a significant cost savings by increasing the pressure in the training fleet to 50 psi. They soon followed up by increasing the pressure in the patrol fleet to 44 psi. For liability reasons, most agencies are reluctant to exceed the maximum pressure listed on the tire for actual patrol vehicles, but they reap the cost saving when going to 50 psi on training vehicles."

But they don't really go into why the tire wouldn't wear down the middle more. Or maybe I missed something. It makes sense that an overinflated tire would wear more down the middle and not quite as much down the sides.

Also, how much is safe? On my yaris its 44 PSI just like the crown vic in that article. But at one point they say 100 PSI is being used, at another they say gains were noticed at only a 10 PSI increase is enough. How do I know how high to go?

[brucepick]

Thanks for considering all this. I estimate it's new territory for just about everyone that reads the article.

I think there's a lot of judgement call involved in determining tire pressure.

The 100 psi was to support the 2-wheeling stunt in the photo, which was done on a closed track. I think it's easy to understand that the tires would hold their shape better at 100 psi. If I recall, they did say they wouldn't recommend that kind of pressure for regular driving. I certainly wouldn't recommend it for regular driving!

My own approach was to use the article's information to get an idea of what levels of pressure can be helpful and safe. Also, you'll likely find your own reasons to limit the psi increase at some point. I found that when I increased it far enough, I didn't like the results any more. So I backed off a bit and that's the pressure I ended up with.

Eventually when increasing pressure, I find the ride gets too hard even for my taste. That's easy to decide of course, and if you hit that point you let some air out. If your significant other is the first one to object, then you get to decide which to let out. (sorry, I couldn't resist)

Also, at very high pressures, handling can get very "light". I don't consider that a good thing. By that, I mean at some point well over the sidewall imprint psi, every tiny twitch of the steering wheel results in an immediate change of direction, because the contact patch has become so small that you really are riding mostly on the center of the tread. However, that's not going to happen at 45 or even at 50 psi, in my experience at least.

Remember that tire pressure will increase about 1 psi for each 10 degree increase in outside temperature. Also it will increase about 4-5 psi from driving. The tire manufacturers are fully aware of the increases due to air temp and driving, so I take any stated pressure specification to mean "cold pressure". So when checking pressure, I do it in the a.m. after the car has sat overnight. Hopefully most mornings have approx the same outdoor air temperature. Measuring that way, you are comparing apples to apples.

[Photonfanatic]

Originally Posted by brucepick

Also, at very high pressures, handling can get very "light". I don't consider that a good thing. By that, I mean at some point well over the sidewall imprint psi, every tiny twitch of the steering wheel results in an immediate change of direction, because the contact patch has become so small that you really are riding mostly on the center of the tread. However, that's not going to happen at 45 or even at 50 psi, in my experience at least.

That is what makes sense to me. And it contradicts the article. IIRC, they say that only the old bias ply tires would "stretch" on the tread contact area itself, and that the newer technology of radials had steel belts inside it that prevented this. If that were true, then you wouldn't get any of the effects that you just described when overinflating tires. Except perhaps a reduction in ride quality.

[California98Civic]

Originally Posted by Photonfanatic

That is what makes sense to me. And it contradicts the article. IIRC, they say that only the old bias ply tires would "stretch" on the tread contact area itself, and that the newer technology of radials had steel belts inside it that prevented this. If that were true, then you wouldn't get any of the effects that you just described when overinflating tires. Except perhaps a reduction in ride quality.

For the last 15000 miles my old baldies have been up at 53-60psi (sidewall the usual 44). For my tame driving style, they are fine. The ride is rougher. The wear does not show any great unevenness that I can discern, though I have to say these tires were spent when I started over-inflating. I get noticeable rolling resistance benefits in familiar places that I used to coast through. For years before I found EM, I used to coast the last big downhill before work, use it for speed up the last uphill, hold at 35mph until a specific spot ahead of my right turn onto campus. Doing that nearly always allowed me to drift into the entrance road at 5-10 mph. When I do that now I enter at 15-20 mph (so I have reduced my approach speed/throttle, saving gas up that hill).