ok let try the convertions functions

1 mile = 1.609 kilometer
so 400 miles = 643.6 km
My car suck 8 liter/100Km (optimals consomation at an average 130kmh/81mph)
so (643.6*8)/100 = 51.488 liter for 643.6 km.
Gasoline cost is 6.39FRF/liter cost for 400 miles is : 329 FRF
Oups I've to convert in USD 7.198 FRF per $
329/7.198 = 45.7 $
Interesting we have the quite the same cost !
But I will be first

if I recall good your speed limit is 70mph no ?
btw my car is a Megane Renaut :
not the best car but at least I can pay it
