Britain’s real best-selling cars are revealed today for the first time. An Autocar magazine investigation designed to coincide with this week’s Budget has lifted the lid on secret industry documents that show what private buyers really spend their money on – and it’s a very different story from the picture car manufacturers paint.

Ford says its Focus hatchback has been the number one car for 45 of the past 46 months – but it is dislodged in the real top 10 by its smaller sibling, the Ford Fiesta (see full table overleaf).

The official top 10 includes fleet sales – cars bought in bulk as company cars. A staggering 56% of new cars sold in Britain are company vehicles – bought not for quality, desirability or handling, but because of discounts, future values and running costs.

Strip away these business sales and you’re left with the real top 10. Every car at the top of the retail chart is a super-mini or city car, except the Ford Focus and Volkswagen Golf. The premium BMW Mini makes eighth slot. It’s proof that super-minis are the most popular private purchase as consumers downsize to smaller cars, which are invariably cheaper to run, insure and repair.

Steve Sutcliffe, Autocar editor, said: "Our research shows that the Chancellor shouldn’t be hammering Britain’s motorists. They are already the most heavily taxed motorists in Europe and are switching to smaller, more efficient cars. The UK’s enthusiasm for cars has not been dulled by extortionate taxes, rising insurance costs and road charges as the government had wished. The car remains the number one choice for transport in the UK."

A Society of Manufacturers and Traders spokesman said: "Current predictions are for 450,000 sales this March alone – the fleet element of that is worth £3 billion to UK. Fleet sales are hugely important to the car industry and the wider economy".

Autocar’s research uncovered the cars that private buyers shun – with some surprising results. The Vauxhall Vectra, for instance, is bought predominantly by fleets with 84% of sales going to the corporate sector. That’s the highest fleet penetration of any model and private buyers bought fewer than 8000 in 2003. The full results of Autocar’s research are below:

CARS WITH HIGHEST % OF FLEET SALES IN 2003

Fleet sales are monitored by the Society of Motor Manufacturers and Traders, which counts any car registered to a business with 25 cars or more as a fleet sale. Sales to any company with fewer than 25 cars are counted as business sales.