GT in 1997.
GT 2 in 1999.
GT3 in 2001 (new engine, PS2). 4 years after GT.
GT4 in 2004.
GT5 in 2010. (new engine, PS3). 9 years after GT3.
GT6 in 2013.
Gran Turismo Sport in 2017 (new engine, PS4) with less content than previous GT, less than half the cars, less tracks, etc. 7 years after GT5. Sure they added content but it was released with a lot less content than previous GT.
GT6 they released it the same year as the PS4. Did they release it for PS4? No. I asked myself why? At least make it cross gen if not a launch exclusive for the PS4. Look how much they take to release a new GT for the next gen with a new engine.
Forgot to say GT5 had a lot of content and the PS3 was difficult to work but the PS4 is a lot easier. They were releasing two numbered GT for each PS before the next PS came out. GT6 came out with the PS4 being sold. Now with the PS4 they haven't even release a numbered GT for the first time in the PS history. Maybe GT7 will be cross gen but from what i see the PS4 will be the first PS to not have a numbered GT if they make it exclusive for the PS5.
I lost my faith in PD... i don't expect anything from them. 10 years after GT5 the first GT for the PS3 and still they haven't even announced or say anything about GT7. GTS is like hey let's release at least something with Gran Turismo name on it for the PS4...