Yes, with 1/5th scale you are mainly stuck with what the car manufacturers put out. You might want to try contacting
[email protected] Their website at
www.fmb.at is down at the moment, but I've uploaded their product list here
http://www.thetechshed.co.uk/Karo-PRL.pdf
In 1/5 scale they list Alfa 155, BMMW M3 GTR, Merceds C200 and Opel Calibra.