One other thing to note is that the protocol runs a bit slower in a real car than it does with just the ECU on a bench.

In the car you can talk directly to the ECU in Ford mode but the Gateway ECU is still there chatting away on the same databus, and I think that this slows things down, or, you can go through the Gateway ECU but then you are talking to one ECU through another, which also slows it down.