The BMW 135i is a great car. It's a blast to drive thanks to its fantastic handling and responsive turbocharged engine. Still, there are always ways to make a car better. A nice cylinder-count upgrade is one wonderful way to do just that. This is the route a German BMW owner went with their 135i, and the upgraded engine came out of a M3.
The noise is excellent. The power is greater. The resulting ride must be amazing. There's not much to go on from this video, but it certainly shows that the 135i here has been butched way up.
Assuming this S65 is the 4.0-liter variety and not the 4.4-liter, it's good for 414 horsepower and 300 pound-feet of torque. It's also a five-time winner of the International Engine of the Year award. It might not have as much power as the Dinan 1M, but it certainly sounds a whole lot meaner.
This BMW proves that the old thinking of big engine-small car is a great philosophy.