I would love to see these championships cars and tracks
DTM
LMS
BTCC
WTCC
V8SUPERCAR
F1
WRC
This was my notion too. Not quite as detailed as Earth's marvelous posts, but very similar. I'd also like some FIA GT Classes added in there too.
If I recall, GT2 or 3 had some series which repeated the theme, but with increasingly difficult A.I. and more powerful vehicles at higher levels. Likewise better cash rewards and cars. So I'd love to see DTM races for instance at Beginner Level, Semi-Pro Level and Professional Level, each with more laps, more competitive bots, bigger credit and car prizes. They should run on tracks that are either German/European, or have that environment flavor such as Deep Forest. The Nordschleife would make a great final event to cap it off. Unlike Fugitivo, I'd prefer that PD produce a wealth of tracks appropriate for any racing series, though according to Lucas Ordonez, we're going to be very happy with the track list in GT6 so here's hoping.
One thing that will be crucial for a concept like this is for PD to produce a whole gob of cars for these scenarios. The good thing is that most of these cars can be duplicates with different liveries, such as what we have now in GT5 with the numerous Super GT Supras, NSXs and Skylines. License as many team liveries as you can, and to add to the potential competitor count, I'd be fine with some fantasy teams and liveries to flesh all that out. But along with that, select bot competitor names that reflect the racing series that you're in, such as mostly Japanese names for Super GT events, European names for DTM and GT Class racing, mostly Americans for ALMS and NASCAR, etc.
However, how about something including his user content idea?
Hot Hatch Championship
Buy a race car from the list or Race Mod it with your own livery (and yeah, I forgot the race cars, meh)
Acura RSX Type-S '04-08
Citroën C4 Coupe 2.0VTS '05
Ford Escort '97
Ford Focus ST '06
Honda ACCORD Euro-R '02
Honda CIVIC TYPE R (EK) '98
Honda CIVIC TYPE R '08
Hyundai Tiburon GT '01
Lancia DELTA HF Integrale Evoluzione '91
Mazda DEMIO SPORT '03
Mazda Mazda 3
Mini Cooper S '07
Nissan 350Z (Z33, EU) '03
Peugeot 205 Turbo 16 '85
Peugeot 206 CC '01
Scion FR-S '12
Scion TC '12
Toyota ALTEZZA RS200 '98
Toyota SPRINTER TRUENO GT-APEX (AE86 Shuichi Shigeno Version) '00
Volkswagen Bora V6 4MOTION '01
Volkswagen Golf V GTI '05
Volkswagen Golf VI R '10
Volkswagen Scirocco R '10
(or whatever, I'm beat and the PS3 is in the livingroom currently)
Homologation to 500PP (and not sure if this is anywhere near right, this is just off the top of my head)
Maximum 299 bhp
Minimum weight 1900 lbs, at least Stage 1 weight reduction
Racing suspension, clutch, brakes, wheels, transmission
Sports Soft tires
Aero kits allowed
Custom livery for your car, use supplied number plate, choose unique number no higher than 499
Points awarded per position
1st - 10
2nd - 9
3rd - 8
4th - 7
5th - 6
6th - 5
7th - 4
8th - 3
9th - 2
10th to last - 1 (or whatever system rocks)
Tracks (Semi-Pro Level)
Deep Forest - 5 laps
Mondello Park - 7 laps
George-V Paris - 5 laps
Hockenheim - 5 laps
Lausitzring - 5 laps
Oschersleben - 7 laps
Sachsenring - 7 miles
Mugello - 4 laps
Nurburgring Nordschleife GP Circuit - 2 laps for the grand finale
Prize credits and cars, yadda yadda, it's getting late. One thing I like in Forza is this bonus system for credits:
Racing guideline off: +5%
Damage on: +10%
Manual transmission: +10%
Clutch: +10%
Driving aids off: +15%
By the way, among some of the sites on the web which list race courses in some detail is this little gem which include maps:
The Racing Line