I am considering trading my '02 Buick Lesabre for a '05 CTS. Are there any known problems with this vehicle. I did find a site that suggested the rear diff. was weak, but that was on first year (2003) models and has since been addressed. Anything else I should know about. It has 70000 kms (43000 miles). It was an Enterprise lease/rental from California. Any info much appreciated.