One question i do have is about the balance of efficiency. Currently the aircraft taxi's out with four engines running at idle power & on completion of engine start the APU is shut down. The new way will involve just the APU with the tug taking all the strain of moving the aircraft. These are tugs have large diesel engines & don't have the same kind of exhaust particle filtration that is now a legal requirement at German airports. It would be interesting to see a true comparison.
hmmm[:?] Interesting point you've made there - I wonder if anyone has thought about that? Maybe they have but would rather have the media kudos;)
VS.