Problem is...
One of the key components of the automotive injection system is not compatible with avgas. The oxygen sensor is a key sensor for determining proper mixture. Unfortuately all O2 sensors to date are quickly killed by the lead in avgas.
There are some homebuilt aircraft here in the states that are using the trusted & mechanically proven bullet-proof lycoming engine but with modern ignition and injection fitted. Great combination. But, for them to run in "closed loop" mode with O2 sensor, they're limited to mogas.
HOSS-1