Hey Richard,
Looks like the model I used has been discontinued:
Retired Car Seats - Britax USA
See the
companion on the link above.
I'm not sure if the one you linked to will fit. I think some stores will let you test-fit in the parking lot with a floor model.
Next step is upgrading the seat-belts in your Carrera
Make sure everything is snug.
Have fun. My son loved/loves riding in sports cars.