Is there any way a base 2015 GS 350 AWD could have better MPG’s than a 2014 IS 350 AWD F Sport, such that F Sport tuning diminishes MPG’s?

Thanks!

 

Is there any way a base 2015 GS 350 AWD could have better MPG’s than a 2014 IS 350 AWD F Sport, such that F Sport tuning diminishes MPG’s?

Thanks!

 

Gearing and curb weight will have a lot to do with MPGs. I believe the engines are identical but one could be mapped differently.

 

The F Sport engine is the same as the base engine. No modifications are made to the F Sport engine.

 

Variables such as engine break-in, quality of gas, different driving habits. The cars do have the same engine and similar weights, different aerodynamics/co.drag. So to answer your question, yes the mileage can go both ways

 

Okay; thank you very much, Gentlemen!

Anyone know if the engines are mapped differently? Maybe there’s different transmission gearing? Or the exhaust setup could be different as well?

 

Thanks for your reply.

Hmm, before I get involved in another MPG mess, wish there was a way to know.

No matter what I do, I've always gotten dismal MPG's in my IS; hope only due to F Sport.

 

I drive mostly stop and go city miles, say 60/40 and I generally get about 18 to 20MPG on my 2013 AWD GS FSport. I tend to drive fast on the expressway but best I have gotten was 28MPG cruising at about 65MPH.

In theory though under normal driving conditions the IS350 would get better MPGs as it is about 500lbs lighter.

 

It should be the same between both IS and GS 350s. The IS 250 loaner I got had worse MPG than my GS I think cause I keep revving it to get more power out of it Vs. the 350 engine u barely tap it and it flies.

 

They should be about identical. That is to say, unimpressive. GS weighs a bit more, but if memory serves, it is also has a touch less drag. Call it a wash?

 

Same here. I kept it in Sport mode and the revs were always high. The 250 is not for me.

 

I assume this is based on your disappointment with your IS350 AWD F Sport mileage and desire to trade it in for a GS350 AWD, and hoping you will achieve better mileage.

There isn't anything specific to an F Sport IS that would give it better or worse mileage than a standard IS. Given that an AWD GS350 weighs about 230 lbs more, I would suspect a GS would not get better mileage than your IS, assuming your IS is working properly.

EPA estimates for the AWD GS are 19/26/21, which is the same rating as the IS350 AWD.

 

Go to GS forum, some people have bad mileage with GS too. It's not the car it's how you drive and traffic condition, etc. These cars are not exactly green car to begin with.

 

Factor in tires and width as well (rolling resistance). I believe the GS AWD has a narrower square setup vs the IS F Sport AWD with the staggered (and "fat" 255s in the rear).

Same transfer case UF1AE and same A760H 6-speed automatic tranny in both GS AWD and IS AWD with virtually identical ratios.

 

You hit the nail on head, JDR76.

Unfortunately, yes, I've noticed that the EPA estimates are identical. :|

Argh.

Thanks.