The Mercedes-Benz M103
The most robust, bad-ass inline 6 cylinder engine Mercedes-Benz has ever built. For a chunk of money can be enhanced to a twin turbo boost monster or a screaming 10,000 RPM rev demon.
My 1989 Mercedes-Benz is powered by The Mercedes-Benz M103 engine, has 200,000 miles on it and I still think I will die before it does.