They are technically right, it is only against one car, in terms of it can only be used for one car at a time, but generally most insurers will add an amount of discount for a second car if you're adding it to the policy. If however you split the cars off to different companies, you'll most likely start at 0 on the Fiesta, despite it being insured last year. I think the only way of getting 2x NCB on a multicar policy is if there are 2 drivers, each gets 1 year if you set it up correctly. Thats what I did in 2012, 2 cars, 2 people, one person collecting NCB on each car.