Honestly,

Look around at the size of most grown Americans.

Crossfire is a 94.5 inch wheelbase car. An awful lot of Americans are just too big/tall/FAT to fit into these little cars. Seriously, something like 60% of the adults in the USA are overweight. A large portion are technically obese.
Why do you think so many people drive around in school bus sized SUVs ?

The Crossfire is a delightful little sports car.

But it's just too small for a lot of US drivers.

The original 2001 Crossfire concept car had a 105 inch wheelbase. When Karmann/DCX adapted it for the SLK platform it was shrunken down to fit.

I'm 6'4", and it's a mighty tight fit. I wear a flat-top haircut and have to see my barber often otherwise I'll rub on the headliner ! I don't care, I love it anyway...

Cheers,

Slim