Saga and Endsleigh have been branded the worst performers in a survey of 16 insurance websites.
In a damning report by Cheshire-based Ci Research, Saga's site was slammed for bland presentation, for taking an average 28 seconds to download pages and for failing to include the full policy wording.
It also omitted to mention its secure booking facility until after a quote had been accepted. This, according to the study, could be off-putting to visitors concerned about keeping their credit card details safe.
Endsleigh's site content was criticised for being difficult to read and providing no facility to save quotes.
It offered the most expensive quotation for the type of driver and vehicle provided, while Tesco offered the cheapest.
The survey compared sites on speed, security, presentation, price and ease of obtaining cover. Some sites, including Eaglestar, Direct Line and Axa's motor site, provided good examples of how to deliver insurance services.
Director of Ci Research Mike Power said: “Insurers have spent millions of pounds on their websites; now they should be seeing a return on their investment. This research was done to highlight good and bad practice in the industry.”
The report highlights variations of up to 50% in quotes on the prices of motor insurance.
And while some insurers required just a few personal details to provide a quote, one required 22 pages to be filled out.
A spokeswoman for Saga said the company's website had been produced on the basis of research done with customers.
“Our customers wanted a site that was easy to use and not too flashy. It is not designed for twentysomethings by twentysomethings.”
She said Saga was implementing plans to put the full policy wording on the site.
Endsleigh marketing manager Stuart Wartalski said: “There have been internet magazines doing research into websites and without exception we have appeared in the top five. But subjective research can produce quirky results.”
Five of the sites surveyed would not provide quotes until an email address had been entered and four did not provide online purchasing.
The research findings can be read at ci-research.com.