Consider what you have for certain:
1) GT5P tracks and possible variations in GT5 (some exist in GT5P)
- Suzuka (that's probably one location, 3 variations)
- High Speed Ring (1 location, 2 variations if you count HSR Reverse)
- Fuji (1 location, 3 variations like in GT4)
- London (1 location, maybe 2 variations also)
- Eiger (1 location, 2 variations if you count Eiger Reverse)
- Daytona (1 location, 2 variations)
This amounts already to:
6 locations, 14 variations
2) GT5Demo track and possible variations in GT5
- Indianapolis (1 location, 2 variations)
this leads to:
7 locations, 16 variations
3) Tracks we have reason to believe will be in GT5
- Nurburgring (1 location, 3 variations - NS, GP, NS+GP)
- La Sarthe (1 location, 2 variations ... maybe 3 if they have Bugatti)
- Madrid (1 location, nothing known about variations but I will assume 2)
- Rome (1 location, nothing known about variations but I will assume 2)
- Tokyo (1 location, 2 variations if you include Reverse)
- Top Gear (1 location, nothing known about variations but I will assume 2)
- Rally track (Tuscany, 1 location, nothing known about variations but I will assume 2)
And this gets us to:
- 14 locations, with 31, maybe 32 variations
I will now be speculative and will add to the list:
- Spa-Francorchamps (1 location, 2 variations)
- Tsukuba (1 location, 2 variations)
And find a total of "most certain" 16 locations with 35 or 36 variations.
I'm only missing 4 locations then. But I'm missing a lot of variations. That's why I remain hopeful that "locations" don't mean "tracks", because that would mean each track had to have between 3 and 4 variations each. I don't think that's possible.