lobuxracer

iTrader: (2)

Apples and oranges. I am talking strictly fuel weight. The current tank is 17.4 gallons, not 15 as you originally posted. To get the kind of range you want with the mileage you expect with the low fuel light coming on at 3 gallons to go (current config) you need a 25 gallon tank. I am keenly aware gasoline averages 6 pounds per gallon, I have worked weight and balance on aircraft and on race cars. Every time I have filled up with the low fuel light on and my range at or very near zero, I've put in 14.2 gallons. I have gone 398 highway miles on 14.2 gallons. Around town, that will never happen with a 4034 pound curb weight vehicle. The wife sees 16 - 18 mpg on her GS F, so to get 400 miles regardless of the low fuel light, you'd need 25 gallons and you'd have to run it dry at 16 mpg.

To get 400 miles with the mileage you are getting assuming you drive until the range is zero with the fuel low light on, you'd need 23.2 gallon capacity. 5.8 gallons of fuel for your specific use case. ~35 pounds of fuel with no consideration for tank weight at all.

All current GS models have a 17.4 gallon fuel capacity. There is always room, it's just a question of how the designers decide to use it. It would seem trunk capacity was a priority (which is why they redesigned the rear suspension to move the springs inboard and reduce the shock tower diameter for more trunk space) and fuel capacity at 17.4 gallons was considered adequate.

gsfdream

im new to the gsf forum just bought mine 2 weeks ago and love it so far,
but i have been only able to get 16mpg city when i baby the crap out of it.
so how are you guys saying ur getting up to 20ish in the city??