Hard to know what condition the Top Gear one was in with regard to fuelling/boost/actuator etc and also what the road wind conditions were like ( head wind/tail wind etc ) if it was the one down on the autobahn?

However, the British mags figures were done on the bowl at Millbrook in most cases (or occasionally Montlhery near Paris ) which is a small bowl compared to Nardo where the Ford official figures were done. The test facility at Lommel was used a lot by Ford but for top speed runs/max speed durability runs on the Cosworths, Nardo was usually preferred as it is an eight mile bowl and much kinder to tyres as the steering angle/heat build-up in the tyres is less than on a smaller bowl.
You can usually say that about another 3 or 4 mph can be added on to Millbrook bowl figures if the car were to run on the Nardo facility or a big straight test track
such as Ehra-Lessien that VW use