It can be seen the serial numbers jumped around a bit. Also interesting is that the year of your car as listed on the title may not coincide with the serial number of shipment. In my case, my cars show as a 1957 AC Ace AEX200 and a 1957 AC Aceca Bristol BEX 590. From the serial numbers, these cars appear to belong in the 1956 model year. While visiting the factory at Thames Ditton once, I checked into this and found that while my cars do appear to have been built in the 1956 time frame as indicated by the serial number listing, they were not delivered until 1957, hence the 1957 identification on the official paperwork.