MPC made two Howmet turbine cars. First there was a coupe called the Howmet TX which raced in 1968 in the 24 Hours of Daytona, the 12 hour Sebring race, Le Mans, and some US endurance races. This kit was out around 1970, and never re-released, as far as I know.
Later, there was a roadster that was a modification of a Can Am McKee Mk 6 I think, and i think it never actually raced. This was called the Howmet TX Mk II.
AMT re-reeased the roadster a few years ago as the "MPC Can Am" in their "Buyer's Choice " series. I've been fooling around with building one of these with a proper Can Am-style V-8 engine in it, but it won't be done soon.
That lawnmower-looking thing was a pusher tractor that was included in the MPC Indy Lotus Turbine Wedge, not the Howmet. I have a few of them now and don't really know what they're good for.
Rick