The SLK32 has 17" wheels, and I believe smaller diameter tires overall compared to ours. It's effective gearing may be lower due to this. (ie quicker off the line if weight is the same, however I see curb weight quoted at 3,220)

I'm willing to bet the performance differences are very slim, almost nonexistent, between the two.

Ours just looks better on the outside (and the slk32 on the inside!)