Complex sentence: A prototype was built, with a body by SARO, to the maximum permitted width of 7ft 6in, fitted with a turbocharged version of the Leyland O.350 engine, which was transversely mounted at the rear of the sub frame.
Split into simpler sentences: A prototype was built, with a body by SARO, to the maximum permitted width of 7ft 6in. It was fitted with a turbocharged version of the Leyland O.350 engine, which was transversely mounted at the rear of the sub frame.