Because of their infuriating ads, I wouldn't even use them to get a vague idea of costs. I have used the other lot with the very slightly less annoying ads to get a ballpark figure. Once I had discovered that the sum was not too extortionate, I phoned the insurers for the other car (e-sure) who hadn't quoted on the comparison site and got the insurance for considerably less than the cheapest quote compare the fluffy animals came up with. I never put a phone number into web forms unless I really have to (and then I seem to make trypos...) to avoid sales calls - if a company does get through to me without me supplying the number, I speak to a supervisor and tell them that as a result of them calling, they have guaranteed that theyt will NOT get my business.