Best thing I can think of if doing mid policy is to be on monthly payments then just stop your policy prior to getting a new car and hopefully it won't be too far in so you don't lose so much of the year that you would've gained of no claims bonus and make a new policy but you still lose money however you do it.

Loads of people seem to buy new cars all the time so just wondering does everyone leave it till insurance expires or just whenever they fancy.