Hi.

On my plane engines the throttle opening vs rpm is not linear:

Half open throttle = approx. 8500 RPM
Fully open throttle = approx. 12400 RPM

It is not the same type of carburators, but the function is the same.

It makes good sense, that you can drive a car as fast with a modest throttle finger instead of idle/fully open throttle. My guess is that the perhaps last 3000 RPM is the RPM range that really needs A LOT of fuel to achieve.

Cheers

EDIT: I could make some tests next year and calculate the RPM's with 1/4, 1/2, 3/4 and 1/1 open throttle. Could be alot of fun