Toyota’s soon-to-be-scrapped MR2 is Britain’s most desirable used car, according to Auto Trader.

It’s a claim questioned by car values specialist CAP Motor Research, but the two-seater roadster tops a new index based on more than three years of model search data from the autotrader.co.uk website.

Auto Trader, which says it attracts more than four million unique online users a month, puts the MR2 ahead of the Porsche 911.

Its top 10 contains another Toyota sports model, the Celica. This, too, is to be dropped from the Japanese manufacturer’s UK line-up towards the end of next year as neither meets Euro IV emissions standards. The manufacturer says that the cost of re-engineering them to meet the new legislation is not balanced by the models’ low sales volume, although it doesn’t rule out replacements in the future.

Of the MR2 and Celica’s Desirability Index rating, a Toyota (GB) spokesman comments: “It just goes to show that as soon as you announce the end of a model line people want to snap them up.”

Jim Murray-Jones, head of digital services at Auto Trader, says the index is configured to correlate new car sales against web searches. To qualify for inclusion in the listing, each of the 125 models featured had to be on sale from the end of 2000 through to 2004, selling at a minimum of 5,000 units in that period.

“The results are startling,” he says. “For every MR2 sold in Britain there were 310 searches on autotrader.co.uk. At the other end of the scale there were only three searches for every Vauxhall Agila.

“By tracking our customers we can identify purchasing trends. Our new desirability index is the first of its kind, and we believe it gives dealers a powerful insight into the potential desirability and value of more than 100 models.”

CAP is startled by the findings. CAP Monitor managing editor Mark Norman describes the index as “an unusual way of forecasting value” and doubts that claimed desirability reflects true market value.

“Pound notes are always the best way. It’s what someone’s actually prepared to pay for a used car that counts,” he says. He also points out that while the MR2 is expected to retain 52% of its original price at three years/30,000 miles, a Mini Cooper – which is not listed because it only went on sale in 2001 – has a 72% residual value forecast.

Similarly, the BMW 7-series is shown as the fourth most desirable car. Its CAP RV rating is 44% at 3/30 while the BMW X5 (also not listed) has a 76% forecast.

Industry analysis and forecasting supplier Spyder Automotive developed the system for Auto Trader. Managing director Jay Nagley, AM’s Market Trends columnist, says: “The study not only shows which cars do well in absolute terms but how similar cars fare against each other. For example, each VW Golf had 13 times as many searches as each Rover 45; a perfect reflection of their relative desirability.”