First I have been lurking for a few months, lots of good info here; thanks.

Question:
Anyone notice a considerable loss of mileage when the temp goes up? We have been averaging 46-50 but now the temps have gone from 70's-low 80's to high 90's we are getting 38-41. Same roads, same gas station, same driving habits, A/C always on and lots of hills.
Clif

With all other conditions the same, an increase in temperature should help mileage, not hurt.

But if the A/C is being used more, that could easily eat up your fuel economy.

I know my mileage will soon take a hit, I'm comfortable without A/C with temps in the 80's. Once it hits the 90's, the A/C will get a workout.

Regards,

I see my milage go up when the temp goes up, only if my a/c is off. The a/c might be coming on more because of the higher temps. I try and keep it set at 80 - 82, this seems to make the time in between compressor cycles longer. When I've set it at 70 the compressor comes on alot more and I see the need for assit on the batteries more too. Kevin

2004 silverblue 5 sp.

Lower temps and humidity increase compression and make a vehicle run more efficiently, heat kills this. That is why there are cold air intakes on cars and even after market intakes are made this way. I am not saying that heat is bad for this machine but if it isn't why is it for every other car made except this one?
Clif

A bunch of Insight owners are using a warm air intake system, they are running a length of preheater duct over to the upper catalytic converter to pull in the warm air into the engine.

This is proven to increase mileage during the colder months.

Cold air will increase horsepower, but warm air increases combustion efficiency, if my understanding of all of this is correct.

Regards,

I can buy that in the cold months but what about the heat of summer? I am guessing I am the only one who is seeing this based on the responses.
Clif

I think it has more to do with your ac being on than anything else.

My hydroponics experiment

You ever notice how hard it is to lip read cartoon characters?
"Crazy is what the sane call Delta Flyer"

This may have little to do with the Civic, but in my Accord, the increased mileage that comes with warmer weather more than compensates for the A/C. The drain on a 4 cylinder may affect it more than my v6.

'05 Accord Hybrid
'05 Odyssey EX-L
'03 1800 Goldwing
'98 Civic EX (16 yr. old daughter's)

So by increased mileage do you mean above what it drops from winter fuel or are you saying because of the heat your car runs better?
Where you at out west? (Big Spring is my hometown)

Traded for above-Custom intake, 2 1/4" ehaust w/Hedman Pack (pn 25005)

Hey, Duc. I live in Albany - have a business in Abilene.

I think it's the consensus here that heat improves FE. Obviously, A/C hurts it. At least in my case, the heat improves more than the a/c hurts - an overall improvement in the summer.

Where's Buda?

'05 Accord Hybrid
'05 Odyssey EX-L
'03 1800 Goldwing
'98 Civic EX (16 yr. old daughter's)