[s-cars] Fuel Tank Size

[Trevor]

Noticed over the past few fills, even if I run the tank down to an indicated
empty, so needle at the bottom of the red, the E comes on & the fuel symbol
pops up. That I can never squeeze more than 17.5Gallons into tank.

Is this what others see?
The manual says tanks is like 21Gallons, so where are the missing gallons.

BTW, I get about 350 miles on a tank.

Cheers
Trev.