Two ways to look at this. How do you define fun? If you want something that will do 150mph +, lose you your licence and even earn you a stretch, then yes, Boxster, Z4M, etc. Though actually a Z4M is a beautiful looking but horrible car with particularly bad steering. The 3.0i is better. And the 335i coupe is a vastly better car than either. Alternatively you can have enormous low speed fun in something like a Suzuki Swift 1.5 or a Mazda 2 1.3TS2 simply because they steer and handle fantastically well.