Overview: Maserati’s latest effort comes under the scrutiny of Jeremy Clarkson as supercar designers strive to produce a truly successful four-door saloon car. He road tests the company’s new Quattroporte model, and finds other supercars that put passengers near the top on the list of design priorities. Tiff Needell tests two modern replicas — one for racing, one for the road — of one of the most exclusive race cars ever built: the 5.0 litre Jaguar XJ 13.