Dude, this is a report-worthy post, I'd cool off - and edit it - if I were you... just a heads up.
Anyhow, as others have remarked - why am I usually fashionably late to the parties around here? - this is going to be something major in many ways. Spec II in Prologue increased the content and features tremendously, and I expect some big changes and additions. I suggest the easily excited and impressionable ignore my wish list.
Spec II
- Massive increase of A-Spec and B-Spec events.
- XP system overhaul, perhaps even deleted.
- Improved bot A.I.
- Comprehensive stat tracking database, including records for each race.
- Possible DLC in the update, including a track or two, a number of cars, optional wheels for Standards, and other things.
- The Paint Shop will now have a range of paints for sale! Imagine that.

- Standards to have a cockpit view (black interior) with basic dashboard.
- Adjustable driver views.
- Additional bodykits, including those for a number of Standard cars.
- Massive increase in Race Mod car list.
- A basic Livery Editor.
- Improved damage.
- Improved physics, most noticeably Rally physics.
- Improved Dealerships, Used Car lots and tuning options.
- The classic tuning adjustments from previous Gran Turismo games return, with additional features including tuning saves.
- Save in pits in any race.
- Event Generator, both off and online, including prizes.
- Massive overhaul of the online system with numerous additional features, Race Series Designer and Event Generator, leaderboards, sharing and selling system, and other goodies.
- Improved Photo Mode.
- Improved Course Maker.
- Drag racing and Touge.
- More more MORE!

DLC
- Tracks from all previous Gran Turismos offered, and will incorporate in single player offline games with included patches.
- New tracks to include Dubai, Brands Hatch, Spa, Hockenheim and Batthurst, as well as American courses. Tracks will be themed to provide racing in different leagues such as DTM and BTCC.
- Car packs such as Standard to Premium updates, Ferraris, Lamborghinis and other supercars, race cars, classics. Car packs will be large, 20 or more.
- DLC will either be free or affordable. I expect some freebies.
Whew... hyping myself a bit much, but... who cares! Whatever it will be will be pure chewing satisfaction.
And for a quick edit, I wouldn't expect dozens of tracks and hundreds of cars real soon. Remember, 6 man-months per car, up to
2 man-years per Premium track, so I'd expect the Gran Turismo Standard tracks to be offered in any numbers first, with a new Premium track here and there. And Standards to be converted to Premiums at an apparent snail's pace.