Franc, the 2003 SLK and the Crossfire both have a 94.5" wheelbase. Actual length of the SLK was 157.9" where the Crossfire is 159.8"
I do find it interesting that most of us over 6' tall, some how have been able to find a comfortable driving position in the intimate confines of the Crossfire without hacking up the cars interior.
I always thought the Roadster had even more head room than the coupe. (While driving my Daughter's XF roadster, it sure seems like it does).
I'll admit, I had to change my normal driving position when I purchased the Crossfire. (Since I've always had a car with reclining seats since 1970) I use to drive in a much more laid back manner. Where as now I drive sitting much more upright than before. In doing so, I've found that I don't get the neck pain that I use to get after long trips.
As for not having rack & pinion steering, it's affected me not one bit. Of course I don't track my car. But when a "stock" Crossfire can out slalom a Ford GT, then it's good enough for me.