For the pre-paid pay-per-mile policies, you will be notified through your mobile app when you are approaching the limit of miles that you’ve already paid for. At this point you can top up by paying for extra miles. Be warned, however, if you’ve underestimated your annual mileage to get a cheaper price and run out of miles several months before your policy ends, you may be charged a higher per-mile rate for topping up, or even risk having your policy cancelled. For some, however, it doesn’t matter if you exceed your estimated mileage. By Miles, for example (four out of five stars on Defaqto, five stars Moneyfacts, 4.7 stars on Trustpilot) charges each month for the miles you drive, whether you estimated five miles and drove 500, or estimated 500 and only drove five.