You seem to be declaring that your experience is controlled test data?
You cant really compare engines when they are in different chassis's either. Aerodynamics etc will play a big difference. Look at a 1.8 Focus Mk1. The Estate and Saloon are significantly more aerodynamic.
So it'd be fair to assume that the TT is a lot more aerodynamic than a Focus then?

I'm not declaring it 'controlled test data', but I find it extremely unlikely that the test conditions consistently work in favour of SUL. This isn't something I've tried over a tank for each fuel, this was a consistent trend over 8 months.