Wow, two completely different cars! Before giving advice, are you going to keep which ever you decide on stock? …… I like the E63 AMG but that's just me. One of those BMW's, modified, showed up at the race track and went into limp mode. (overheating) It was a bullet for 3 minutes, more or less. If I bought an E63 I'd leave it stock. If I bought the 135 I'd modify it and regret it later …. and be called gay …. by haters …. or in the know …. I can't say. I've never driven either of them. All I have are impressions. Get the Mustang?

Les