We got quotes for 100 different people using four different price comparison sites. To make the figures easier to read, we have listed them in order of increasing premiums.The first row shows the cheapest quotes we found, for people who could pay yearly.

The cheapest quote rarely matched up with the cheapest deposit however. Most of the lowest priced insurers asked for fairly high deposits, or didn't even offer any monthly terms at all. So, the second column shows the lowest deposts we were able to find for that particular motorist.

The third column shows the total cost the motorist would have paid, if that person had accepted the 'pay monthly' quotation.

The fourth column shows whether or not the insurer offering the lowest quote was also the one offering the lowest deposit.

In a massive 81% of cases, the insurer with the lowest basic quote DID NOT offer the lowest deposit. When this happened the difference between the total premium that a monthy paying client, with a small deposit, would have to pay, and the one that a yearly-paying customer could get, could be very large indeed.

If we look at the first and cheapest premium, for example, the motorist would have paid £168.52 for one lump sum, or £264.41 for monthly payments. That's a difference of £95.89, or an eye-watering flat 56.9%. Over a year this equates to an APR of 92.59%; an absolutely horrendous figure. If we look at the most expensive policy, at 4163.67, grows to £4901.66 if the cheapest deposit option is selected; an increase of £737.99, or a flat 17.7%, or an APR of about 31.21%.

Clearly, in both these cases it may have been a lot cheaper for the applicant to raise the cost of the premium elsewhere.