Ian Huntley's red Ford Fiesta has a fake registration J112 YR5G which does not conform to any of the three formats that have been used in the UK: ABC 123D (1963-1984), A123 BCD (1984-2001) or AB12 CDE (2001-present). This was probably done to avoid any possible similarity between his registration and a real-life one.
In the first episode 11mins 42secs Ian drives off the main road on to a dirt track the car shown is a Vauxhall nova/Astra not the red fiesta shown in the next shot