not sure where to post this- mods move it if you need to

my gas milage has dropped a bit since winter, will the following things effect it in any way? - these are the only things that have changed since i was checking my milage in the winter, same driving pattern, no other mods
its summer so my top is always down- i thought this could hurt cruising at highway speeds

in june i got new wheels/ tires- 18x9.5 in the front , 18 x 10.5 in the rear

and could the 'summer gas mix' have anything to do with it?

i plan on going in for a dyno tune sometime late august, if that matters

 

How much worse is it ? that's an important piece of information

 

around 26 highway in december
around 21 highway now

 

check around for the simple things, like air filter, fuel system, and tire pressure, you'd be suprised at what low tire pressures can do lol

 

if your car was sitting for a long period of time (over winter) then the gas could have gone bad and plugged up your fuel system... that would be my guess... also how many miles on the car? maybe you need new plugs?

 

= shitty gas mileage
theres the answer

haha

well things like driving with your top down, hotter outside air, "summer mix" gas might affect the mileage. i dont think the bigger wheels will make that much difference, unless its on a lifted truck. like stated above i would check your plugs, your airfilter, and anything else directly involved with the fuel/intake systems.

 

id have to agree with everyone else... check your filter and plugs first.. then my next guess would be youre fuel lines

 

i say seafoam your car. just follow the sticky i wrote above if you've never done it before.

FWIW, my old V6 3.4L firebird used to get 18mpg in the winter and 22-23mpg in the summer every year that i had it. the warm-up time in the winter killed my mileage and engines are more efficient when they run hot in the summer. the fact that your winter mpg is better than your summer mpg is scary.

on the upside, my old V6 was more powerful in the winter. in the heat of summer it was soooo slow, i could mash it at a standstill and not even squeek the tires. it would just go...slowly...

those tires will hurt your mileage. they're a lot heavier than stock wheels and take more effort to push - but they won't kill 5mpg worth!

 

the 10% ethanol mix thats everywhere doesnt help either

 

that's another thing that drives me nuts. the purpose of ethanol, at least what was PORTRAYED to the public, was to save oil by blending ethanol into it. theoretically, we should be using 10% less oil, right? i think it's a scam. who benefits?

1.) the USA. they have to buy less crude stocks now.
2.) big farmers. they'll sell oodles of corn.
3.) refineries and gas companies. now they have even more things to refine. more $$$ for them.
4.) oil companies. the ethanol drops our mpg = more trips the pump for consumers

what do we see?

1.) less fuel mpg = more trips to the pump
2.) no decrease in fuel prices
3.) ethanol was never made to run in most engines so it can't be doing any GOOD to our cars

we actually LOSE by the switch to ethanol. the customer loses mpg and pays more, the government and big subsidized farms make money, along with the oil companies since we frequent the pump more with the ethanol blend. who's benefitting here? it's all a game. we lose, but the media makes it look like it's beneficial because it's a "bio-fuel" and everything with the word "bio" in it is portrayed to be good. ever hear of "bio-hazard"? thanks for lying to us.

 

Sad thing is, this was true for me. I went from 245/50/16 16 x 8 stockers to 315/35/17 17 x 11 AFS ZR-1s, and I dropped hwy mpg from 26 to 21 mpg.

 

ok...i'll check my air filter, tire pressure, have the plugs checked when i have it tuned
its my dd so it wasnt sitting for a long period of time

 

change the wheels through a tank of gas and see if that makes the difference up