For all those who have done an ECU tune, I was wondering whether you noticed any significant effect on gas mileage. I'm thinking there is a presumable decrease, if so, how much? I'm talking daily driving, mostly freeway but also some local. Not much "spirited driving" other than passing slower cars as I deal with LA traffic.

For reference, I have a 2012 IS250 and I bought it as a daily driver so I was more interested in good gas mileage (IS350 was fun but I couldn't get more than average 19-21MPG compared to average 26-27MPG in the IS250). Now that it's finally paid off and nearing end of warranty, time to try some mods. So I'm particularly interested in hearing from those who have the TTFS Frank Smith ECU tune for IS250 but would also appreciate impressions from other tuned 2IS models. Thanks.

 

I've had my ECU tuned for nearly a year now and the gas mileage has been about the same as it was prior to the tune. I typically get 18-19 MPG with city driving and 24 MPG on road trips/highway driving.

 

Gas mileage will depend on how you drive. The tune will not effect gas mileage.

 

Thanks for the responses. I was thinking that if the tuned car puts out more horsepower then it would be using more gas. But it sounds like the tune just gets you to speed faster, and thereafter it just depends on how you use it.

 

Yeah that's kind of a weird street in the world of cars haha. You'll find out actually that most things that add HP also increase MPG (other than blowers and extra cylinders blah blah..) It does so because it's increasing the overall efficiency of the engine. This means you get both HP and MPG, but usually the MPG appears to go down because people change their driving habits.

 

Nice. I'm sold on the tune then.