MediaBuyerPlanner: General Motors is offering $1.99-a-gallon fuel for buyers of certain vehicles in California and Florida, Brandweek reports. Those customers must also enroll in the OnStar vehicle diagnostic service.

The discount comes in the form of a rebate for the difference between the average price per gallon of premium fuel in buyers' states, and the $1.99 per gallon figure. The money is applied monthly to a pre-paid card. The credits are good until Dec. 3. Marketing begins today and includes broadcast, print and interactive.