Extremely light cars, cheap to purchase initially, cheap to modify and get reliable power, cheap to maintain (in comparison with other club cars). You cannot get a naturally aspirated piston powered car to produce the same horsepower to cubic capacity without spending a bit of coin, not to mention the weight of the motor per cube. Datsun 1600 gets close, but is going to be down on power unless you get a twin cam engine.
All early rotaries have a strut front end which dicate a coil-over shock suspension. RX2's have a multi-link rear end with a solid axle, it wasn't until the RX7 was released when they re-introduced the watts-linkage rear end. Discounting the behemoth RX5, useful only as a boat anchor and a source for 13B motors. Oh and the rear discs. Off the top of my head RX2/Capella's weighed in at 960kg, where the 808/RX3 was 880.