Wow - nice performance for the flow rate on the TB20. The leaning can be done at any altitude - but the higher altitude does give a better flow rate for the speed.
I am leaning using the G1000 and balancing the EGT/CHT, so it can be improved by the assist function and LOP ( reading the Lyco info they imply a 2-3 gph difference - but for maintenance reasons dont recommend LOP!). But Im not going to get anywhere near your figures. Im told by the salesman (
) that he has got it down below 11 gph - but Ive not had the chance the play too much. Ive only done about 30 hours in her, with flights that have kept me very busy.
I spent ages going thru the performance figures before I purchased, it would dissapointing to think others wouldnt.
One of the interesting things I found when looking at planes (new and esp. used) was the difference between the quoted useful load and then real figures when looking at the actual weight certificates. They were much heaver than "promo" figures, especially on planes loaded with avionics.
I would expect the new Cessna's to be much better aerodynamically and improve on all of the key performance figures. And will probably launch with a Lyco. BUT even North America will start to suffer the problem of lead in AvGas (seperate transport etc.etc.) and they will either opt for lower octane unleaded or go JetA1? So the equations for performance wont be so clear cut.