After Frank is injected with the 'nanochip', he is driving the Audi with license plate MB 970 AS to the French-Swiss border. However, when he is pulled over by the Swiss border guards and the scene cuts to Dieter's trailer, Dieter is seen working on the same Audi bearing license plate, MB 970 AS.
Later, when Frank arrives at the drop-off point in Geneva, the Audi's license plate has now changed to BK 845 UR. But in the next scene when Frank is talking to Carla while still in Geneva, his Audi license plate is back to MB 970 AS.
Then, after Frank leaves the Audi at the Geneva airport in a helicopter and flies to Nice to meet Carla at the airport, she is waiting for him with the same Audi, MB 970 AS.