Scalextric Cars: Do you buy Sport or Crystal Case?

Hi,

I have been buying for a year now almost all my scalex in Sport edition. What about you?
Do you think it's only a marketing trick from Scalex to make us buy cars more expensive or is it really worth it? I have read that the engine should be better but to be honest I have nerver really seen the difference. Besides sometimes I regret not having the crystal case for those car. The cartoon boxes are nice but mine are always closed for lack of room to expose its opened.

Maverick.