Oh well, I contacted Audi by email about three days ago to ask about the availability of the 1.4 Tfsi cylinder-on-demand for the A3. They just called today, and said they checked with the product group, and don't expect it to be available to order before the summer (June at the earliest).
I guess they just lost a customer then, as I would like a new car delivered by the summer!
Having read many reviews on the new A3 and the new Golf, the new 1.4 Tfsi engine seems to be the best in term of performance, noise and economy, making buying the 2.0 TDI a bit pointless (unless driving a large number of miles), particularly as a company car given the bad BIK rate, and the 122 bhp 1.4 Tfsi irrelevant (probably higher consumption for less power), with a BIK rate 2% higher than the 140 bhp version. The new 2.0 TDI does not seem to fare well in term of real consumption either, seems to make start/stop quite bad and S-tronic gearbox does not seem to be smooth.
Given the excellent reviews and level of equipment of the Golf 7 1.4 Tsi GT DSG CoD, I don't think it will be a wrong choice anyway.
The only issue is that I will need a get a 5-door one, as VW is preventing UK buyers to get DSG on 3-door Golf. Those people from VW and Audi are just annoying with their artificial restrictions, specifically on UK buyers...