I copied the following information from an interesting thread found at GameFaqs. Threads on GameFaqs can only go to 500 posts, then they become locked, and are soon are purged. I thought that I should post some of it here for the sake of posterity.

Most of the following information was translated from a Japanese website and presented by two GameFaqs users: itazura_da (gs) and toga1976. Please note that the author of the Japanese site presents these ideas as theories and doesn't claim to have definitive answers...

1. Maxing out points (overall, machine, course, battle) can be accomplished using just one car from each of four "classes". These classes are referred to as A, B, C ,and D and seem to correspond, respectively, to normal, tuned, race, and special cars. The classes are further divided into A1, A2, B1, B2, C1, C2, D1, and D2. I'm not sure how these "classes" are determined or confirmed (that point doesn't seem to get much attention on the Japanese site), but the author has a table showing the classes to which each car belongs. Tuning a car can change its class designation. Setting opposing car strength to -2 through -10 not only permits managing the race for gradual/steady passing (ensuring high battle points), it also allows you to conduct much of the race in "slow down" or "cruise" mode, which in turn ensures high course points by keeping your driver on the track.

2. The author provides tables showing which cars, tunings, tracks, opponent levels, etc. he used in order to max out B-spec scores using only family cup races ( http://www.geocities.jp/j8ba7yrg/gt4/7_10000.html ). There are two tables -- the first details the first 7000 points (100 machine, 70 course, 70 battle), and the second details the remaining 3000 points.

3. Achieving the first 7000 points can be done using only four cars on the Nurburgring. However, the cars need to be tuned in various ways to cover all of the A-D "subclasses". The cars used by the author of the site are listed below (my apologies if these model names do not correspond exactly with the English designations...Im just translating without referring to an English language list):

A-1: Volkswagen Lupo 1.4 '02, default;

A-2: Mazda Roadster 1800 RS (NB) '04, default

B-1: Mazda Roadster 1800 RS (NB) '04, default + supercharger

B-2: Mazda Roadster 1800 RS (NB) '04, default + stage 3 turbo

C-1: Toyota RSC Rally Raid '02, default

C-2: Toyota RSC Rally Raid '02, default + medium racing tires

D-1: Nissan Fairlady Z Concept LM Race Car '02, default

D-2: Nissan Fairlady Z Concept LM Race Car '02, default + stage 3 turbo

As Toga rightly clarified earlier, the author of the Japanese page still considers all of this a work in progress, and IS NOT trying to say that these are the ONLY cars that can be used, or that this is the only combination or order of races. He has concluded, however, that better results are obtained if you start racing with the A-1 cars and work your way up to the D-2 cars when running the Nurburgring races.

He also proposes some more detailed theories about point breakdowns. For instance, he speculates on this page ( http://www.geocities.jp/j8ba7yrg/gt4/10000_3.html ) , based on his test results, that the initial 7000 points are broken down as follows: 586 points for class A-1 cars, 737 points for class A-2, 901 points for class B-1, 1077 each for classes B-2 and C-1, 983 points for class C-2, 878 points for class D-1, and 761 points for class D-2. The remaining 3000 points, he speculates, are divided evenly (750 points each) between car classes A, B, C and D. He further suggests that the first 7000 points impact machine skill, course skill, and battle skill, and that attaining 7000 points should yield machine, course, and battle skills of 100, 70 and 70, respectively. The final 3,000 points impact only course and battle skills.

4. The remaining 3000 points require races at the remaining tracks using the same four cars, with no need to alter tunings to achieve different "subclasses". For the final 3000 points, the author uses:

A: VW Lupo 1.4 '02, default + medium racing tires

B: Mazda Roadster 1800 RS (NB) '04, default + supercharger + medium racing tires

C: Toyota RSC Rally Raid Car '02, default + medium racing tires

D: Nissan Fairlady Z Concept LM Race Car '02, default

5. As for strategy, the key point is this: you need to focus on battle points, the other points will come just by running the tracks with the different cars. For each of the "final 3000 point" races, it should be possible to obtain approximately 13 B-SPEC points, of which (the author speculates) 4 are battle points and 9 are course points. Actually, on another page, he speculates in more detail that the final 3000 points are broken down into 750 points per car category (A-D), spread out over 58 courses, such that each course yields 12.93103... points. He speculates that course points are doled out at 8.620 points per track and battle points at 4.310 points per track. Gaining the full battle points for each race is the big obstactle, and the author did some testing and concluded that the key is to NOT PASS THE OPPOSITION TOO QUICKLY or finish the race with TOO BIG A LEAD.

6. That last point requires its own bullet! The author did some testing and found that passing too many opposing cars in roughly the first 12 seconds of a race can reduce battle points awarded. So he adopted a strategy of downgrading the opponent level to a point where the B-Spec driver can be paced in "slow down" mode to lag back and not pass until at least about 13 seconds into the race (or at Nurburging, before the first hairpin), then not run away from the competition. As a result, in all of the races shown in his tables, the opposition skill level has been set at between -2 and -10. He points out that strategies for pacing will vary depending upon whether the race has a grid or rolling start. and will also be impacted by the length of the course. But in any case, the key is to try to hold back, then pass at least a few cars, finishing either in first or in some other position without a large gap between B-Spec driver and opposing cars.

7. Using the above approach, the author reached 10,000 100, 100, 100 in only 267 races (and actually WINNING all of the family cups, for good measure, although winning them is not necessary).

Only time will tell who the first GTPlaneter to get to 10,000/100/100/100 will be.