The RMD was introduced to the market in 1949 as a drop-head (convertible) model, in order to have a wider range of offerings for the Riley RM. It used the 2.5L inline-four capable of 100hp mated to a four-speed gearbox. In contrary to the RMC model that was focused on the North American market, the RMD was more focused to the English and European market. Production ended in 1951 with just over 500 being produced.