It has already sold one Saab outlet and closed one Saturn dealership, leaving it with 11 dealerships in the USA representing Jaguar, Land Rover and Aston Martin.
The closures, coupled with a drop in Land Rover registrations in America, have led the revenue generated by its USA operation to drop from £94.8 million to £77.4 million.
Gross profit margin has dipped from 16.8% to 16.4%, however the underlying operating margin has crashed from 3% to 0.4%.
Nationally, registrations in the US were down 10% at the end of the first half of 2008.
Chief executive Trevor Finn said the revenue decline has been mitigated by an increase in revenue from the used vehicle sales operation following the implementation of a used car sales programme, but gross margins have weakened slightly as a result of the shift in sales mix towards used vehicles.