Gas mileage went down?
05-01-2010, 10:37 AM
#1
3rd Gear Member
Thread Starter
Join Date: Sep 2007
Location: Sacramento, CA
Posts: 734
Gas mileage went down?
Alright, I just got back from a car show down in LA. I drive over 1000 miles on the freeway during the week and the car says I got an average of 20mpg. Same time last year with the same mods I got about 22-23mpg. What gives?
Anyone have any ideas on what I should check? I pumped the tires up to 36psi and made sure all the fluids were topped off. I guess maybe I need to clean my air filter? It does look a little dirty.
Anyone have any ideas on what I should check? I pumped the tires up to 36psi and made sure all the fluids were topped off. I guess maybe I need to clean my air filter? It does look a little dirty.
05-01-2010, 10:50 AM
#3
4th Gear Member
Join Date: Nov 2008
Location: California
Posts: 1,495
I don't think a dirty air filter has much to do with mpg on a computer controlled car. The computer adjusts the A/F ratio. A dirty air filter can affect the performance.
I wonder whether the gasoline blend changed over the past year (e.g., more ethanol in the gas now).
I wonder whether the gasoline blend changed over the past year (e.g., more ethanol in the gas now).
05-01-2010, 11:35 AM
#4
3rd Gear Member
Thread Starter
Join Date: Sep 2007
Location: Sacramento, CA
Posts: 734
Yep, I also reset it on the way back just to check to make sure it was right and it instantly went to 20mpg. Other cars I was with (2x 08 bullitts) both got around 24-25mpg. I cant remember but I think I got a retune a while ago from bamachips and maybe he put too much fuel in.
Forgot to add also my car did the failsafe mode when I jumped on it after having it in cruise control from a while. I guess its that TSB where the car stutters after cruising for a while when you get on it. Mine actually killed the engine and I had to turn it back on at freeway speeds.
Forgot to add also my car did the failsafe mode when I jumped on it after having it in cruise control from a while. I guess its that TSB where the car stutters after cruising for a while when you get on it. Mine actually killed the engine and I had to turn it back on at freeway speeds.
05-01-2010, 12:35 PM
#8
6th Gear Member
Temperature, humidity, wind speed and direction, difference in % of ethanol in the fuel, cruising speed, tire pressure, spark plugs, load in the vehicle, road surface... Any of these or combination of these plus quite a few other factors can affect gas mileage. I have years and over 1 million miles of mileage records and differences in fuel consumption on the same vehicle and what you consider identical conditions is the rule and not the exception.
People think they're going to get XX.X MPG on the highway and XY.Z city, period. They're quite mistaken.
People think they're going to get XX.X MPG on the highway and XY.Z city, period. They're quite mistaken.
05-01-2010, 05:34 PM
#10
3rd Gear Member
Thread Starter
Join Date: Sep 2007
Location: Sacramento, CA
Posts: 734
Temperature, humidity, wind speed and direction, difference in % of ethanol in the fuel, cruising speed, tire pressure, spark plugs, load in the vehicle, road surface... Any of these or combination of these plus quite a few other factors can affect gas mileage. I have years and over 1 million miles of mileage records and differences in fuel consumption on the same vehicle and what you consider identical conditions is the rule and not the exception.
People think they're going to get XX.X MPG on the highway and XY.Z city, period. They're quite mistaken.
People think they're going to get XX.X MPG on the highway and XY.Z city, period. They're quite mistaken.