My 2017 GSF is having horrible fuel economy. I have modified the full cat-back but something is off. I average around 350km per tank... but I am quite sprited in driving.

Wondering if the car is getting older at 50k (km), or is it the old spark plugs that is causing this problem?

 

217 miles out of one tank is pretty normal for spirited driving.

 

I see. When the car was brand new it was getting around 400-450. But now it is closer to 350.

Thought it was the spark plugs, but maybe my driving just got more aggressive XD

 

I'm usually getting 250-275 miles on a tank. I can live with poor gas mileage, but that fuel tank size will always be a design blunder to me.

 

I am typically getting 190ish - 220ish miles per tank with heavy-spirited driving but I rarely am doing highway driving. I can live with the mpg, not the end of the world.

 

No one buys a V8 with MPG in mind. V8=SPG

 

Without taking the car on the highway, I’m getting 16-17mpg and about 230 before the low fuel warning comes on.
I don’t mind the mpg with this type of vehicle. Wish the tank is little bigger though.

 

That mirrors my experience and wishes. Another 4 gallons would be really, really nice.

 

Just want to make sure my GSF is running efficiently. Agreed that the fuel tank should be bigger.

My 17 R8 drinks alot of gas, but it had a 95 liter tank instead of a 65.

 

Worlds smallest gas tank for the size of the car.

 

The gsf tank is 17.4 gallon. I believe The light comes on early. I think around 12-13 gas. Which means you have another 4-5 gallons to go. I routinely drove my Camry 80-100 miles after the gas light comes on and the gas needle is typically way below the E (empty) sign. I have not pushed my GSF too far below 0 range but pretty sure there is much left after the light comes on. Just note how much it takes at fill up and subtract that for 17.4. to see your reserve.

 

My E60 M5 had a 50 liter tank. I think most performance versions of cars have smaller fuel tanks to accommodate for rear axle and diff design and also weight saving.

My GSF came with a stupid spare tire that protruded into the trunk! On normal GS cars, the tires are below the trunk.

My C63 AMG has a 50 liter tank, while my wife's C300 has an 80 liter tank!

 

The winter blends in gas are less efficient and the colder denser air puts more drag on the car as well.
I have noticed a couple of MPG drop recently as well.

 

Glad you've finally come around. Only been a few years of ownership for you to get to this point.

https://www.clublexus.com/forums/gs-...fuel-tank.html

Randy B

 

Short trips or long trips? Highway cruise, or stop and go or spirited? Cold weather or Hot weather? they all make a huge difference in MPG.