I couldn't open the link either though I gather it includes a pic of a Grinnall Scorpion 3. The S3 is built by Grinnall Specialist Cars in England. A few more than 300 S3s have been built and they are scattered around the globe with, depending on who is counting, from about 22 to more than 40 in the U S. The cars are built to accommodate either the K75 through K1100 drivetrains or the K1200 drivetrain depending on the purchaser's preference. Very soon, a new chassis will be ready for sale which will acomodate the new transverse K engine/drivetrain.
The S3 is a very modern interpretation of the Morgan three wheeler concept. It handles exceptionally well at speed and is extremely stable. In England and most markets, S3s can be purchased/ordered complete with factory warranted BMW drivetrains. Here in the U S, the drill is to buy the car from Grinnall either as a box of parts or assembled without the drivetrain. A stock, properly assembled and sorted GS3 is a well engineered vehicle. A few, mine included have been modified and enhanced to improve servicability, durability and touring comfort/convenience.
My #220 is for sale. If you are seriously interested, I can furnish details and refer you to folks who know S3s and #220 in particular. This is not a fire sale or a cheap car; though it is offered at about the cost of parts in today's market; and was built by a superior craftsman. Not me. It includes many enhancements and is ready to drive anywhere with paved roads!.