More than 16,500 cars change hands every weekend, according to the Automobile Association.

After the latest change on registration plates on September 1, that total is set to soar in the next few weeks as drivers upgrade one of the most important status symbols.

David Motton, consumer editor at What Car? magazine, said: "Canniest buyers hold back until the end of September, when the salesman has to work harder for a sale, and gives you more attention because there are fewer customers around.

"But people who want the first new registration plate in the street sitting in their drive are unlikely to wait."

In theory, buyers are in a strong bargaining position.

Many are flush with cash, on paper if not in their pocket, after seeing the value of their bricks and mortar soar.

For car buyers still in work, prospects are brighter still.

Rock-bottom interest rates could go even lower and wages are slowly creeping ahead while car prices fall.

The Alliance & Leicester car price index says average prices are down by almost 13 per cent in the past three years.

Some cars cost 21.5 per cent less than when the index was first issued in June 1999, against property price rises of 50.3 per cent in the same period.

Andy Bayes, of Alliance &

Leicester, said: "New cars are more affordable than ever before. When the index began, it took 30.6 weeks for someone on average earnings to earn the price of an average new car (£11,971). In June this year, it takes only 22.6 weeks, with the average car costing £10,445."

Buying a new car should be plain sailing. But many buyers waste hundreds, even thousands, of pounds in the showroom.

Research from moneysupermarket.com, a web site where consumers compare the cost of personal finance products, says it is easy to waste £2,000 by not shopping around for the best deal on a new car.

On a new Peugeot 206, a buyer with a ten per cent deposit and a three-year finance deal provided by the manufacturer repays a total £12,867.

Anybody taking the cheapest loan on the web site pays only £10,563, saving £2,303.

On a Ford Fiesta 1.4 fivedoor Ghia, anybody putting down ten per cent and taking the manufacturer's loan package pays £12,585.

Buyers on the seven per cent Cahoot flexible loan get away with £10,635, saving almost £1,950.

Moneysupermarket.com
sales director Richard Mason said: "Though car prices have fallen by up to 20 per cent over the past year, buyers may fail to take advantage of this saving because they opt for expensive finance deals.

"With incredibly low interest rates available from a wide number of loan providers, there is no need for people to take the finance deal offered by a showroom salesman".

Before they even think about finance deals, buyers must find the keenest price.

Others do it on behalf of those who hate to haggle.

Saga Car Direct, launched a year ago to revolutionise car buying for the over-50s, claims to have saved an average of £1,589 per car so far. Average manufacturer's on-the-road price is £13,815, says Saga's Andrew Goodsell, and average price paid is £12,226.

Its biggest savings have been on the Rover 75 1.8 Connoisseur four-door saloon (down £2,830), the Renault Scenic 1.9dTi Expression (down £2,017) and the Nissan Almeria 1.5SE (down £1,929).

What Car? magazine's target price hotline says buyers of the Vauxhall Astra 1.6 can save £800 by haggling, while the £1,000 regularly knocked off Ford Mondeo 1.5 Zetec fivedoor saloons brings it down to £14,564.

Try for £1,500 off the list price of a Land Rover Freelander 1.8 Station Wagon.

When you've chosen the car and agreed the price, how do you pay?

The cheapest method, almost certainly, is to unlock some equity from your home and put it on the mortgage.

For many, this involves a property revaluation and various administration costs but flexible mortgage holders find it much easier to top up their advance.

Virgin One, the bank account mortgage provider, says buyers on flexible mortgages can save £1,600 on a VW Golf.

Personal loans, currently available at rates driven down by fierce competition, look attractive too.

Above £15,000, the AA (free car inspection included), Coop Bank and RAC Financial Services all have packages at less than nine per cent, with other "goodies" thrown in.

Abbey National charges 7.1 per cent on £5,000 to £15,000.

Although 0 per cent car finance deals are commonplace, David Motton at What Car? is sceptical.

He says: "They often require a large deposit and people frequently end up borrowing this elsewhere."

Finance deals from manufacturers invariably cost more. But Mr Motton says salesmen on a big commission to shift the deals may reduce costs if customers show they can get cheaper money elsewhere.

Hire-purchase schemes, involving a series of monthly payments, only transfer ownership of the car when the final payment is made.

But these are being increasingly outflanked by car purchase plans, pioneered by Alliance & Leicester (A&L)

and available at 7.8 per cent to applicants by internet.

The idea has caught on.

Marks & Spencer, Direct Line, Halifax and Royal Bank of Scotland all now provide deferred car purchase loans.

A&L's car purchase plan allows buyers to borrow up to £20,000 over four years by deferring up to 60 per cent of the value of the loan.

Repayments are lower than with hire-purchase and borrowers have three options at the end of the loan term.

They either sell the vehicle and pay off the loan, change the car and use the trade-in value of the old vehicle to clear the deferred amount or they keep the vehicle and continue with the same fixed, low monthly payments until the whole amount is cleared.