Nothing tops off a glitzy car collection quite like a pre-production prototype. In most cases, they look just like the cars that'd wind up in the hands of customers, but many come with small differences and details that set them out as their 'ordinary' counterparts. And of course, there's the historically significant part they played in developing the end product. Naturally, rarity is also part of the appeal but so too is their role in getting a car out to the wider world.Buying one, however, is far from straightforward. Once a prototype has completed its tour of duty, it'll either be stored in the darkest depths of a manufacturer's storage room, stripped for parts or, more often than not, scrapped. The very best examples may find their way into a carmaker's heritage fleet, but seldom do they wind up in private hands and even fewer remain road registered. This Aston Martin Vanquish is one of the lucky few, and it's the only pre-production car of the 22-strong run that'street-legal.However, having spent most of its life on display at Aston Martin's Newport Pagnell factory, this remarkable piece has had only one registered ownerAston Martin Lagondaand has been cherished in pristine condition. With just 670 kilometres (416 miles) on the odometer, it is an exceptional find, combining historical significance with delivery mileage. Silver, £99,999