Oh, HERE is why the M Roadster made the list:

The 2004 stolen vehicle report from CCC Information Services Inc. is based on the rate of theft for a vehicle as a percentage of the total number of that vehicle registered.

It's a percentage of... Basically, if BMW made 100 M Roadsters and 20 were stolen, then that makes a 20% theft rate. Now, if Acura makes 10,000 Integras and 2000 were stolen, that too makes a 20% theft rate. They are the same even though there were 1980 more Integras stolen than 2002 M Roasters. Shitty comparison if you ask me...