Early FLs have Bosch Motronic 7.1 engine management which is Euro 3 compliant. 2001 onwards use Motronic 7.1.1 which is Euro 4 compliant hence also compliant with the ULEZ. The only change in that 0.0.1 version is independent control of the cam timing solenoids and a warning light if the SAI system is broken. Apparently that made all the difference
PF are pre Euro3. No pointlessly complicated emissions gear, just simple catalytic converters
Unfortunately also no tick in the ULEZ box either.