Need help! leon 1.6 tdi or 1.2 Tsi

Hello together Attention, I have no idea of cars. …just so in advance I want to buy a new (used, annual car or similar) car. Somehow everyone tells me something different. I drive 20000 km a year for work (almost only motorway) and then still private something. The Tsi allegedly consumes 4.9 l and has a 6. course. Is this also so with the consumption when I drive on the highway 140? Is this the 6. course good? Or do I have to drive with the tsi 100 to the catalog consumption to come? Or does the diesel make more sense because it has a bigger machine? I hope I have made myself understood?? I would be very happy about your help