Deven

I was wondering if anyone has made note of any changes in MPG between the OEM 18" and OEM F-sport 19".

I have the 2015 GS 450h F-sport, that has 19" asymmetric wheels, but I am not getting the manufactured MPG ratings. I think I am about 10% less.

My suspicion is that probably the ratings are based on the standard 18" wheels. What I do not know is the weight difference between the 18" and 19", and whether or not the rotational mass is significant enough to make a difference. Similarly, are the OEM wheels exactly the same size (circumference) or is there a percentage difference between 18" and 19". The width could also make a difference in rolling resistace I suppose,

Thus, if any of you had 18" OEM wheels, and then changed them out to the F-sport 19" OEM, was there any difference in MPG? If so how much.

AJLex19

Although I cannot speak to the rim size/weight/rotation difference, I have a non-Hybrid base/premium GS350 and I do mostly city driving. The best i've ever seen is 14mpg with very few extras on my car (I have the 18" OEM wheels). Its usually around 11-14mpg in typical stop and go city driving.

The best i've gotten on the highway is 24mpg. My 2001 GS430 with a V8 wasn't too different from this - real world gas mileage is a far cry from the EPA/manufacturer's reported numbers. When I brought this up to my mechanic, he laughed and said "Don't believe everything you read...esp about gas mileage."

Also: Generally speaking, the curb weight of the GS hybrid is higher than the base model GS's as well - this doesn't help with overall real-world MPG.

Deven

Thanks for your thoughts. Looking at some generic web sites, looking at this issues, going from 18" to 19" could give a difference of 5%. Similarly going from winter blend to summer blend gas could also make a significant difference as there would be less ethanol in summer blend? Even if it is 5+% that would all of a sudden make a 10+% difference.

I am not sure we are in summer blend yet.

AJLex19

This site will help answer your question: http://www.eia.gov/todayinenergy/detail.cfm?id=11031

Summer vs. Winter Blend definitely will make a difference as I've had the same conversation with my mechanic uncle.

The only other things I can think of is always driving in Eco mode, easing through accelerations and reducing weight (smaller wheels/tires; get rid of excess in the trunk) to help overall real-world gas mileage.

You can be sure that when they are publishing those EPA numbers, that they are under the most unrealistic driving conditions that you and I could never reproduce in our various commutes. I always wonder how much Cold/Snow/Rain/Sleet/Heat/Wind/Pressure/Humidity and the combination of these conditions are used in these EPA numbers as well.

This article has been passed around the forum a few times as well: http://www.caranddriver.com/features...d-tires-tested