Thread: gas mileage

I get better mpg on the freeway without using CC.

im in the 10 to 14 mpg club as well for city driving.

on the open road doing 75 i can get 30+ if i hit no hills.

Think of it this way.

CC tries to keep you at the same speed all the time, so its always getting on the gas and off the gas, though you hardly notice it. With CC doing that its really reducing your MPG by a small amount, it can vary from 1-3 mpgs (just a good guess). And if hills are involved the CC will downshift the car to increase the speed back up to where you set it and then drop back into overdrive and continue on.

As where if I'm not using CC I can keep my foot on the pedal and not move it and not be on the gas and off the gas like CC would. And when hills come, I can keep my foot planted and only lose a few MPH and not have the car downshift to use more fuel, then when the road becomes flat again I will be right back up to my speed slowly.

Yes its not the best explanation, buts its pretty much true.

Even if there are not many hills or slight upgrades, I still get better mpg not using CC.

Usually average between 23.5-24.5 on average driving, if I'm doing more highway driving it's 25+. The car has it's share of issues that popped up after I bought it this January, but the fuel economy has been pretty good. Granted, the car it replaced was a 1990 Oldsmobile 88 with a pre-series 1 3800 and it got about the same (with almost 140k miles on it).

Kind of funny, also, that my LS1 Firebird averages about 23 or so, but gets closer to 28 mpg's on the highway. I wish I had an LS1 in my GP

19 city/highway mixed. Guzzlin' gas.

Originally Posted by Fivefingerdeathpunch

Think of it this way.

CC tries to keep you at the same speed all the time, so its always getting on the gas and off the gas, though you hardly notice it. With CC doing that its really reducing your MPG by a small amount, it can vary from 1-3 mpgs (just a good guess). And if hills are involved the CC will downshift the car to increase the speed back up to where you set it and then drop back into overdrive and continue on.

As where if I'm not using CC I can keep my foot on the pedal and not move it and not be on the gas and off the gas like CC would. And when hills come, I can keep my foot planted and only lose a few MPH and not have the car downshift to use more fuel, then when the road becomes flat again I will be right back up to my speed slowly.

Yes its not the best explanation, buts its pretty much true.

Good explanation, that is exactly what happens. Drive in a hilly location and you will actually feel it.
CC is good for flat highway , long distances where you want to rest your leg.

What did you gap the plugs to? Did you check for vacuum leaks yet?

I'm getting 18-19 in the city without even trying, though only 25-26 highway. I'm wanting to retune and see where that puts me, I'm getting some decent part throttle KR when the TC is locked.

I'm only getting 16 atm cuz accidentally put slowkar juice in instead of regular or racekar juice in..... derp on my behalf

Originally Posted by PioneerGTP

Do vac leaks cause bad mpg? And i havent checked cause i cant find someone with a vac guage or whatever.
And I dont know, my dad just bought the factory listed spark plugs and wires and installed them while i wasn't there.

Yes, vacuum leaks can interfere with getting optimum MPG. Vac leaks arent monitored, so the MAF,IAT,IAC, arent reading that extra amount of air so the meterization gets thrown off and also it can be dirty air depending on how bad the leak is bc its not being filtered either by your air filter.

If i can remember right, I think the Vac PSI should be around 19-22psi but if u do manage to get the VAC gauge just hook it up to the brake booster line. For a easy quick check, use CARB cleaner and spray on all the VAC lines and listen for the change of the idle.