WELL-TIMED for the autumn car-buying season, Tesco is bringing its formidable High Street muscle to the highly competitive car insurance market with its launch of Tesco Compare.com, its long-awaited price comparison website.

Tesco's unique blend of strategy and brute force reshapes most of the markets it chooses to enter. But a stumbling incursion into estate agency earlier this year shows the retail company does not have everything entirely its own way.

The new site, part of Tesco Personal Finance, went live with 26 brands and will run in tandem with Royal Bank of Scotland (RBOS) -a major player in car insurance that has previously regarded insurance websites with a peg on its nose.

Tesco is likely to expand the site to cover a full range of financial products, bringing it into direct competition with rivals such as moneysupermarket.com, recently floated on the London market for almost £1bn and about to enter the FTSE 250.

Aron Thompson, head of insurance at rival price comparison and switching service website uswitch.com, said: "Tesco Compare.com is backed by RBOS Group which, through various brands such as Churchill, Direct Line and Privilege, and partnerships such as Virgin, Lloyds TSB and Nationwide, controls over 30 per cent of the car insurance market.

"It is a particularly interesting move by a group that, to date, has not allowed any of its brands onto a price comparison service.

"We hope RBS now works with uswitch.com and other comparison sites to create a level playing field, giving consumers a free and open market in which to compare prices."

Curiously, Direct Line this year has run a furious advertising campaign attacking insurance websites, saying customers should consider much more than price alone before choosing a policy. No wonder Peter Dingle, the managing director of Tesco Compare, said: "Our customers want more help in choosing motor insurance. They want more than just the usual 'shop around' for insurance premiums.

"We have placed great emphasis on the fact our site not only compares price, but also looks at individual policy features."

What does the Tesco move mean to consumers?

Though a Big Three has emerged in online car insurance providers -moneysupermarket.com, confused.com (Admiral) and gocompare.com -premiums have risen in recent months.

Sainsbury's Bank Car Insurance Index, analysing online premiums across the market, says the average July premium at £486.43 was up 4.23 per cent on July last year. The average car premium rose £19.80 in the past year.

On average, men pay £518.46 for cover, against £442.28 by women. In the year to July, men's premiums jumped 5.2 per cent, against 3.1 per cent for women.

Debra Williams, the managing director of confused.com, says the credibility of the Tesco site could be undermined by the fact that a quarter of its brands are owned by RBOS.

She said: "While we welcome Tesco into the price comparison market, it is currently one of the least comprehensive services and will need to go some way to convince its customers of its impartiality."

Ms Williams thinks Tesco's site might help consumers keen to buy specific brands.

However, she said: "We find that 'best prices' for many consumers come from smaller insurers who provide niche pricing.

"Unless Tesco significantly increases its panel of insurers, it is highly likely that many, perhaps even most, of its consumers miss out on the cheapest deals."