MILLIONS of people use comparison sites to seek the best deals from across the market, but no one has compared the comparison sites – until now.

Research from Defaqto, an independent research firm, found that quotes can vary by almost 50% between motor-insurance sites.

Despite using the same criteria for a motor insurance quote, five comparison sites provided four different premiums for the same insurer. The highest price was £367.28, from Confused. com while the lowest was from Moneysupermarket, which quoted £248.13 – a 48% difference.

It also found none covered the whole market. Q4Insure, for example, compares only seven insurers and brokers while Moneysupermarket compares 52.

The price-comparison market is estimated to be growing at 30% a year. The most common use is to find car insurance, according to the Resolution Foundation. About 10% of all motor policies in Britain are sold through comparison sites.

Resolution and Defaqto want websites to sign a code of practice because many fail to explain commercial relationships they have with product providers, and risk misleading consumers.

Nine comparison sites were assessed by Resolution in separate research, including Moneyfacts and Moneysupermarket, which provides The Sunday Times with its best-buy tables.

The research commended Fool and Uswitch for the “exemplary” way in which they explained links with sponsors. However, most were less clear about how they generated revenue and how commercial relationships affected their content.

Confused states on both its website and in its TV advertising that it covers 97% of the online market, but Defaqto estimates it covers only 40%.

Confused denies that it is being misleading. It said: “We cover all UK underwriters for motor insurance apart from firms underwritten by the Royal Bank of Scotland (RBS). We have had the 97% figure passed by the Advertising Standards Agency.”

However, it admits that RBS is Britain’s largest motor insurer, underwriting big names like Direct Line, Churchill, Privilege, Tesco, Mint and Virgin.

Here we look at the best comparison sites. The results are based on Resolution research that only compared general sites. The recommendation for car insurance is based on the Defaqto report while energy is based on reports from industry insiders.

Best for car insurance: Tesco Compare

Tescocompare.com offers the most accurate and easily understandable quotes, according to Defaqto. It scored a rating of 87% – 12 percentage points more than its nearest rival, Comparethemarket.com.

Though it compares only 27 insurers or brokers – far fewer than the 52 used by rival Moneysupermarket – Defaqto said the site was the most user-friendly.

It allows customers to compare the details of up to four different quotes at the same time. Its quotes are also the most consistent with prices offered by providers when you click through to their respective sites.

The worst performer was Insurancewide.com, which scored just 50%, because the information provided was confusing and difficult to compare, the report said.

Best for credit cards: Uswitch

The best performers are Moneynet, Uswitch, Moneyextra, Kelkoo and Moneyexpert, which all provide accurate information.

Of these, Uswitch has the most flexibility as it offers the greatest number of ways that products can be sorted – for example, it allows you to search by best rate or best introductory discount and so on.

Worst is Moneysupermarket, according to the Resolution research, because it had an incorrect rate, and Fool, which listed an incorrect length for balance transfers. Moneysupermarket also had one of the lowest levels of flexibility and scored low for explanation of terms. Moneyfacts, meanwhile, listed a product that did not exist.

Best for personal loans: Moneyextra

Out of the six tests comparing quotes with the prices offered by providers, Moneyextra had five that were within £1 of the provider’s monthly repayment quote. It is also one of the most flexible sites for sorting information.

The worst performer was Kelkoo, which consistently provided repayment quotatations that were more than £5 different from the one listed by a provider, as well as having a low level of flexibility and a poor explanation of terms.

Moneysupermarket also had a number of results that were up to £5 different from the one available from the provider as well as a low level of flexibility.

Best for savings: Fool

Moneysupermarket, Moneynet, Kelkoo, Moneyexpert, Fool and Moneyfacts had the best results for accuracy – although of these, Fool came out top in terms of flexibility and explanation of terms.

The worst performer was Moneyextra with two inaccuracies, one of which was an incorrect rate of interest. It also scored poorly in explaining terms, although it did as well as Fool in terms of flexibility.

Best for mortgages: Moneynet

The most consistently accurate results were offered by Moneyextra and Moneynet. However, Moneynet comes out better because it has more flexibility in sorting tables. However, it scored poorly when it came to explaining terms to consumers.

Moneysupermarket had the worst results, with only one out of the six tests coming up with a result that was within £1 of the provider’s repayment quote.

Best for energy: The Energy Shop

Though the Defaqto and Resolution Foundation reports do not cover energy, one of the most accurate and comprehensive sites is TheEnergyShop.com, according to industry experts.

The site sifts through over 9,000 products and covers many smaller specialist providers.

Neither Moneysupermarket nor SimplySwitch show deals from either EBIco or Telecom Plus, though these tend to have more expensive tariffs.

Uswitch, which has had a long-running feud with British Gas, does not allow customers to switch to it through its website, although it does list the supplier on its comparison tables.

TESCO WEBSITE WAS CLEAR AND EASY TO USE

FAYE TATAH, 22, a customer services adviser from County Durham, said she used a number of comparison sites to find motor insurance for her Vauxhall Astra, but not all of them were easy to use.

First she tried Moneysupermarket and Confused but found it difficult to compare prices between providers.

‘The prices between the two sites also varied a lot so I wasn’t sure which one to go for,’ she said.

She was most impressed with Tescocompare. ‘It was much clearer and easier to use and I could also compare the details of up to four deals at a time.’

Tatah, pictured here with her two children, Jackson, two, and Summer, five weeks, said the site did not offer the cheapest quotes, but the details were more easily understood. ‘I wanted to make sure that I had all the things I wanted covered, like a courtesy car. With some of the other comparison sites, it wasn’t always clear.’

She settled for a Lloyds TSB policy at £320 – £160 less than her last bill. The highest quote was £500 from Confused.