draxcaliber

if you really wanted good gas mileage doing n/a mods to your tc, get the ecu programmed with a really lean fuel map. some guy i talked to on the phone with at zpi told me that in some issue of like sport compact, or import tuner or whatever held a contest, and one of the catagories was mpg, so this guy with an impreza had an alternate fuel map and got like 43 mpg. how is that?

Jan06xB

Ideal fuel economy is about 18 to 1 air/fuel ratio unfortunately that makes a lot more emissions and we don't want that . . . right? SO changing the fuel map can get you a lot more MPG and NO2 probably about 30% more MPG.

web

When I first got my car in April, I was getting about 24 mpg (I'm assuming due to the break in period). Through the summer here, I was getting more around 28-29 mpg and that I would assume would be due to heat turning the liquid gas into fumes within the tank. Now, as Fall has settled around the area and the temp is lower, I'm at about 25 mpg again, which I would consider pretty good for the mods on my car. I haven't lost any mpg from my upgrades, which is odd. But, only time will tell and more driving.

paul34

To the few individuals still arguging here... please stop. There's no point. Isotope took the time to do his own test and had his own results - why do you need to attack that? Why not respect it instead? He got his results, maybe you can get some different results.

There's no need to criticize it. I appreciate your test, Isotope, thanks.

hunterUnknown

iTrader: (1)

Indeed, thank you.

Jan06xB

In colder weather the air is more dense and it takes more power and energy to push the car through it. You should also check your tire pressure as that can drop a few psi when the temps go down. You were doing great at 29mpg.

web

Yeah, I've put the fronts up to 35 and the rear are holding at 29. Also, b/c the cold air is denser, you produce a tiny bit more hp with it causing a slight......SLIGHT....decrease in fuel economy. Those numbers may be small, but every little bit counts when trying to squeeze out some mpg.

locondcoco

please, run your own experiment, and give us the results. i tried to do it as well but couldnt keep it up. so respect his results no matter how "controlled" it was.

Jan06xB

Well yes and no - you CAN produce more HP because you can cram more air and thus more fuel into the cylinder because colder air is more dense thus has more O2 per unit volume thus requires more fuel to burn properly. It doesn't mean that you have to however. Just like heavy rain is bad for FE but a light rain is good because the road gets a little more slick reducing friction with the tires and the moisture in the air makes the fuel burn better.

If I were you I would put more air in the rear as well to maintain an equal pressure balance or else the tires will grip differently in a turn and may produce a slide/skid as well as the ABS system likes to "see" equal size tires.

theblue

I thought you needed the friction to keep on going? Can you explain how that works?

Jan06xB

Road surfaces are ruff for traction and most of the time you really don't need as much as they provide. The ruff surface increases rolling resistance and lowers fuel economy. Coming back from Maine a couple of weekends ago I got some of the lowest gas mileage this year until I hit the Mass boarder and then the tire noise reduced and the gas mileage when from the low 30's to almost 40mpg. The light coating of water on the road makes the tires roll over it easier - not a big difference but it helps. Also concrete roads are better for gas mileage as well because they generally are smoother.

tekisui

Someone please put this thread out of its misery. Its long since degenerated...

paul34

Ok, a correction.

Last tank I got 25.21633944 MPG.

This tank I got 29.40287987 MPG! There are too many variables to figure out what exactly led to that, but one thing that was quite different was that I quit accelerating gently up to 2.5k-3k before shifting. I didn't go WOT on each gear, but I gave it a good amount of throttle... hard to explain. Not quite "snap your neck back and RACE" type of accelerating. Maybe a little past 1/4, almost to 1/2 throttle I'd say? Maybe a little past that. Just definitely not floored (that makes the engine run too rich and waste gas).

Also, I changed my severly underinlfated tires to about 36 front/35 rear cold.

We'll see what the future holds for us.

Jan06xB

That's brisk acceleration which is good because the quicker you get out of lower gears the less revolutions your engine makes and the more gas you save.

As far as putting this thread to rest - the first time I drove a tC I got 36mpg - you want to listen to what I do and save some gas? or not? Figure out how much you will spend on gas for 100,000 miles of driving.
Oh yeah and the tC was an automatic.

paul34

what's the most efficient way to drive an auto? I mean, if you try to go the half-WOT/short shifting in an auto, its hard, since if you press harder on the throttle, it'll just take each gear higher (or worse, keep downshifting and forcing revs higher).

what is the best way? (not poking fun or anything, this thread has really got me curious in general!)

Jan06xB

Keep the rpms low <2000 and get above 42mph asap to get into 4th - that's where the best mileage is. My buddy that owns it drove really easy on the gas and now is getting over 30mpg easily.

av1581

I, like Driver18t, stumbled onto this thread while looking for info on the fuel efficiency of the tC as I'm considering getting one in a couple of months. Thanks to those who have actually posted useful info.


This is partly true...but you still don't know what you're talking about. As documented by another poster, the engine would indeed run cooler, but not completely cold. In case you didn't know, friction alone between the metal components in the engine will cause plenty of heat.

Sounds like you've never taken a physics class. There's a HUGE difference between static friction and dynamic friction. In essence, it's MUCH harder to GET the car going, than it is to KEEP it going. FYI, a manual tranny car CAN INDEED roll away if it's in gear when it's on an incline - I've seen it happen before. In the case of coasting down a mountain on purpose, it also has to do with momentum...with gravity pulling the car down, you're essentially getting "free" energy that's giving you enough momentum to overcome the engine friction more easily than you could if the car is stopped.

Sounds like you have a minimal understanding of how an internal combustion engine works and completely lack a basic understanding of physics. Refer to Driver18t's post on page 7 for if you want to read something from someone who knows what they're talking about.

And finally, have any of you ever driven a golf cart with an ICE? The engine shuts off while coasting and doesn't idle at all. The same thing happens in a hybrid car, the ICE won't run unless it's needed, so it shuts off when stopped, when accelerating with the electric motors, and when COASTING. What makes you think this can't be done in a regular car? It's pretty much assumed that when you take your foot off the gas, you want to slow down. Only when the friction gets hard to overcome (read: you slow down enough and the engine's RPM's are low enough) does it kick back in to prevent you from coming to a complete stop too quickly.

web

29.9 mpg from Baltimore to Matthews, NC holding 75 mph on cruise control

nightrider051

my mpg sucks! im lucky if i get 26...and thats not riding the gas too hard either...seems kinda crappy for a 2 cylinder....love the car though

web

2 cylinder?