We normally cruise with 2200 to 2300 rpm, manifold pressure according to altitude (flight level), as we mostly fly WOT (wide open throttle). Leaned to 50F ROP (carburated engine, LOP not really possible). Fuel burn is around 48 l/h (slightly below 13 gph).
These are BTW book values.
PS: fuel prices in Europe are actually 2,8 /l which equals to 14 USD per gallon
Mogas is 1,8 /l = 9 USD per gallon
Markus Vogt, PPL(A) SEP, NFQ, IR, FI(A) rp
D-EEBU, PA28-235B, based Mannheim (EDFM)