are the throttle bodies from a 96 318is compatible with that of the m3?
No sir they're not. There's a considerable size difference between the two motors intake manifolds.
Colin is correct, the 318 has a 4 cylinder engine versus the 6 cylinder of the M3. You could manufacture an adapter plate to fit the M3 throttle body to your manifold but there is no real performance gain that way.
you're joking right?
Looking for a Used 3 Series in your area?
CarGurus has 40,386 nationwide 3 Series listings starting at $1,350.
Search BMW 3 Series Questions
BMW 3 Series Experts