Racing car builder John Cooper (of the Mini-Cooper) constructed a twin-engine Mini-Cooper in the 1960s, though in this case the regular body could be used. It was very fast, and handled very well, but the rear engine/transmission was mounted in a modified front sub-frame, with the steering knuckles welded straight. One of the welds broke when he was driving the car at 100MPH, and the resultant accident almost killed him. But the concept was excellent, and to-day a number of high performance cars are of four-wheel-drive, albeit not with two engines.
It is hard to say if the figures quoted above make sense. The smart is heavy for a micro-car, and this version would be heavier still. I can say that my 1966 Mini-Cooper 1275S, with some simple race modifications, reached 60MPH in about six seconds, but then it weighs only about 1,300 pounds.