colder air is more dense. cold engines require more fuel to run smoothly. when your engine is cold, the gas sprayed by your injectors will change from a vapor back into a liquid when it comes in contact with cold cylanders. once your engine is up to operating temperature, your car will operate its most efficient. the biggest drain on milage is awd. everything else is minimal in comparison. though intake, tbe, head porting,and many other things will help with engine efficiency. gearing is always another huge factor in milage along with aerodynamics.
I dunno about everyone else, buy my mpg stays pretty constant year round. I'm averaging about 22 to 23 mpg during the winter, and about 24 to 26 in the summer. Interesting....
I wouldn't call a drop of 2-3mpg pretty constant. That's around an 8 to 11% difference summer to winter.
I've got some major issues, getting 300-350km on a tank... 98na2.2 with a catback >.> 15street,20highway. I really don't drive fast, it's a doggg of an engine. It likes to throw the CEL for the egr valve malfunction, think that has anything todo with poor mpg? Maybe i just need one of those treatments done, clean the carbon buildup, injector cleaner.. etc.
04 STi - Stealth-back exhaust is the only power mod I get 17-18mpg in the city, 24-25 on the highway. City mileage is a bit worse in the winter, but not much. I tend to let my car idle for 5+ minutes in the winter, but I also drive much less aggressively so it almost balances out... I have taken quite a few road trips and the car is very consistent on mileage, summer or winter.
Well, look at it statistically... when variation is 2+mpg within the season, is a delta of 2-3 across seasons significant? Time for a statistical analysis.... You would need the datapoints, but I am willing to go out on a limb and say that the delta is not statistically significant.
There are some really simple things you can do to improve your gas mileage as for right now. First of all, making sure you have the correct tire pressure or to your preference. The harder the tires, the easier they will roll. But keep in mind that this causes the tires to wear more. Making sure that your air filter is nice and clean. Replacing the pcv valve. Do a fuel system cleaning. Replace the fuel filter. Using the correct oil grade, of course synthetic. Basically keeping up with the maintanance on your car can help you improve you gas mileage.
You could also add the complete STi underbody panel kit to a WRX that doesn't have it...the NASTIOC/Monkey Trunk crew saw an increase in MPG attributable to reduced under-car turbulence. Get FMIC and scoopless hood - that big scoop is stealing at least 3.173 MPG.
Yes, scoopless FTW. I also noticed that when I got rid of the scoop I didn't have that wind rushing sound at highway speeds. I swear I could tell the difference immediately.
Sure to take the thread OT - but what is the minimum turbo req'd to warrant a FMIC w/o being too laggy? Alternatively, how far short would a Pnp'd VF39 fall of being FMIC worthy?
I know what this means now!!! My mpg trick- Metro..... its got 3 cylinders and it uses em all, its got 5th gear, just wont stall.....
Faster tire wear, only if extremely overinflated. His car does not have a PCV valve. Fuel filter is good till 105K.
