Hi PHeMoX,
after you've the mfc42d.dll in your system32 folder you now just need to copy the CarCreator.dll to the med_plugins folder. But I guess you've already done this. In difference to the Tree Creator Plugin there is now no new rider, but a new menu point under the Tools-rider.
And before you blame me for the low-polygon cars that are created. My focus was to create full animated cars with given skin-points. The download also includes a test-car where can be seen which area of the texture belongs to what part of the car.
Greetings
André