The MG J-Type used a Morris/Wolseley overhead-cam four cylinder engine with a crossflow cylinder head - quite advanced for the 1930's. Most J-Types were open two-seat roadsters, though the J1 was a four seater. Also, some bare chassis were built into closed cars by various coachbuilders. The J3 and J4 are interesting, racing-focused models - the engine was downsized under 750cc to meet racing regulations, but was fitted with a supercharger and larger brakes to improve performance.