Will a 1.8 20v apt engine from a 1999 vw passat fit into a 1996 Audi a3?

Yes, a 1.8 20V APT engine from a 1999 VW Passat can fit into a 1996 Audi A3, as both vehicles share similar platform architecture and engine mounting points. However, compatibility may depend on specific components such as the wiring harness, ECU, and exhaust system. It’s advisable to use the Audi A3’s original components where possible to ensure proper integration. Overall, while the swap is feasible, additional modifications may be necessary for optimal performance and functionality.