Maximum rear legroom in 3er GT is about 70mm bigger than in 3er sedan / touring ... Meaning the rear legroom dimensions of 3er GT are somewhere between the rear legroom dimensions of 5er & 7er SWB! While eg. rear legroom of 5er GT sits between 7er SWB & 7er LWB! BMW GTs are very spacious cars!
Maximum rear legroom dimension comparison:
F30/31 3er Sedan/Touring: 891 mm (35.1 in.)
F34 3er Gran Turismo: 960 mm (37.8 in.)
F10/11 5er Sedan/Touring: 917 mm (36.1 in.)
F07 5er Gran Turismo: 1062 mm (41.8 in.)
F01 7er Short Wheel Base: 988 mm (38.9 in.)
F02 7er Long Wheel Base: 1128 mm(44.4 in)
Audi A8 Short Wheel Base: 983 mm (38.7 in.)
So, almost an A8-level of rear legroom ... less than an inch less!