When an insurance company sets its premiums, rrt's going to set higher premiums for that things that include the most risk. If you choose a lower voluntary excess, the insurance company knows that you won't pay much so they will set higher premium. Car loans generally your voluntary excess, the less the insurer has to spend so the reduced your premium goes. So set your voluntary excess as high as it's afford. Websites a nice little discount just by tweaking this when you get your quotes, however, just be sure don't leave yourself out-of-pocket should it is undoubtedly a need to earn a claim.