Many dealers are passing the cash straight on to buyers, while subsidised lease offers are also available that make monthly payments on the $48,775 R-Class lower than several cheaper Mercedes models.
Mercedes fell into loss after electronic bugs tarnished the brand’s image for reliability while its Smart small car business haemorrhaged cash.
However, Mercedes said it remained committed to the long-term success of R-Class, built in Alabama, and said it just had to explain to customers what the model – sold as a "grand sports tourer" – was for.
The car is part of a heavy investment programme that has seen Mercedes expand its line-up to include the B-Class small people carrier and replace much of its range recently. The M-Class SUV was relaunched last year while its mammoth GL sibling will go on sale soon.
The R-Class, which has just been launched in Europe, is advertised as a "grand sports tourer", a segment it claims did not exist before the car went on sale.
Last year Mercedes sold 4,959 of the cars in the US in the three months it was available. It refused to say how this compared with internal targets, but sales are running at half the monthly rate of the M-Class.
All three models are built at the Mercedes factory in Tuscaloosa, Alabama, which has flexibility to switch production between the vehicles. Last year it built 95,600 vehicles, and has annual capacity of 160,000.