OK, you are right, I made a mistake. It should be 160-180 sqm in total.. Sorry mea culpa.....so 80-90 sqm per floor, cca 100 sqm built GF (+- 9x10 m or something like that). + garage cca 40 sqm + terrace cca 15 sqm.
Now that I already know what Grundflächenzahl and Geschossflächenzahl are, I have also found a plot... what do you say about 389 sqm? According to my calculations it could fit.
Grundflächenzahl = 0.4 and Geschossflächenzahl = 0.8 and I am allowed
to build 2 full floors, EG + OG (as full floors according to BayBO)
In terms of size, it could work and in terms of costs... I have already asked 3 people if it would be possible up to 300K, and the answers were "YES" but without outdoor facilities.