SD Sports (Apocalypse)
Larger anti-grav units give more speed and acceleration for Hovercars and other small airborne vehicles.
Source: X-COM Apocalypse Ufopedia
The top of the line Superdynamics engine for very small airborne vehicles. The power of this engine is extreme over the SD Standard. Performance is excellent, acceleration is excellent when used for its intended purpose - to power Hoverbikes.
This engine comes standard on Hovercars. It is a very capable engine which should be used up until the usefulness of Hoverbikes becomes useless. If there is a shortage of SD Sports engines for purchase, then buy up the Phoenix Hovercar and rip out the engine. Sell the Hovercar afterwards.
The size of this engine is 2x2. It is in the small category.
This engine can power a Hawk Air Warrior (the largest terran airborne vehicle), but at reasonable acceleration.