Why are straight cylinder engines more powerful than vee cylinder engines?

[Jax Humanhater]

Ex. BMW 3 series I6 engines are more powerful that the V6.

 

[Hiroshi Awazu]

Not entirely true my good man. for example The current year Ford Mustang V6 has over 300hp Naturally Aspirated were BMW's 335is's 6 is 320hp with a turbo. M cars are another story. But i like em both, not knockin one or the other.

 

[Hampus Andersson]

It has nothing to do with the engine layout. It´s up to the manufacturer to decide how much horsepower they want to extract from an engine.

I myself prefer an n/a BMW straight six, doesn´t have to be a powerful one, i had a 320 M-sport ´04 with 170hp and it was super fun to drive despite the lack of horsepower. Screamed nicely up to the 7.000rpm limit aswell

BMW has never built a V6 engine for a production car either as far as i know.
They have a patented Turbo-layout for a V6 engine that probably will sit in the next M3.