This finding comes from research by dealer systems supplier Pinewood Pinewood into how dealers make use of the data they record about customers for marketing purposes.
A further 41% of dealers only contact the customer when they believe that they will be interested in buying a new car two or three years after the original car sale - and just 20% maintain regular customer contact, according to the study.
Neville Briggs, Pinewood's managing director, says: "Customer relationship management is one of the buzz phrases of the moment in the motor industry but our research shows that the vast majority of dealers are not taking even basic action.
"A large number of franchise dealers are recording detailed data about a customer when they buy a new car and then never make any attempt to contact them again. It shows exactly how far motor industry CRM must improve."
The Pinewood research covered a sample of more than 1,000 franchise dealers, both customers of Pinewood and other DMS systems.