They are different. The eng in the Neon is a Chrysler & the Avenger has a Mitsubishi eng. Both are the same liters but that is it. Funny thing is if we were talking about a Stratus the answer would be yes and no. The Stratus 4dr has the same eng as the Neon but the 2dr is also built on the Mitsubishi Galant platform has the Mitsubishi eng.