Had the opportunity to try out the
2000GT-R yesterday. I tested it at GVS, Suzuka and Monza.
The car is actually great fun to drive and I think that you largely managed to make it quick, fun and still let it show its age well. Managed a low 2.09 time on GVS, so actually closer to your posted times than usually.
When you look at the car, the first thing to strike you is the pretty smallish contact patch of wheels to road. And keeping it historically accurate, means lots of roll - in fact manage that well and you are most of the way there to do fast times in the car. Dive and squat on the other hand seemed largely absent.
In long corners, such as the second and last ones at GVS, the 130R and 200R at Suzuka or the Curva Grande and Parabolica at Monza, the car is wonderfully stable and much more planted than could be expected from its ancient underpinnings. In all of those it was possible to gain time on the more modern competition (I used the lvl 18 Japanese Championship for testing). The key to good lines through such curves is an early (but relatively gentle) turn in, and if you do not touch kerbs (or possibly mid corner bumps, not that there were any for real testing on those tracks) the rear will stay nicely in line.
Back to roll - I am sure you could have minimized it and gotten a faster car as a result, however that would simply make it a modern, anonymous experience and obliterate the car's DNA. As it is, the car will not exactly fly through corner combinations - the roll unsettles it a bit so you either let it do its own thing (i.e. let go off the throttle), which means a fairly benign and stress free passing of corner combinations, or if you want faster times, manhandle it through. A well judged quick 'dab of oppo(site lock)' will suffice to battle the roll induced oversteer, if you misjudge it a bit (and I am sure this is less of an issue with a wheel than the DS3), the back will oscillate for a while before settling again - just letting go off the throttle is usually not a solution here anymore.
Taking the second section of GVS as an example, the corners between the first sector time measurement and the first tunnel will usually go quite smoothly if you avoid the kerbs, if you go over them without throttle application or at least in a fairly straight line - kerb hopping and steering at the same time is too much for the suspension. Getting on the gas too early out of the first tunnel will also produce monumental amounts of smoke.
If you approach a relatively slow corner without applying throttle, the basic balance is slight understeer (low grip at the front), not of a FF variety but enough to necessitate a slightly early turn in. The understeer is instantly correctable by unsettling the car by a throttle prod (or kerb or bump), which works fairly well for accellerating out of slow corners for instance. If you want a fast time, a fine judgement is required, though, as the grip afforded will produce more wheelspin than traction if you are not careful. Generally the roll induced oversteer is easily controllable, it just costs time. The good thing is the car gives you options and allows for different approaches to corners for drivers with different driving styles.
So understanding the limits of the car is probably key (speak of a tautology) to fast times - it is not a modern 4WD wonder, which will flatter the driver no matter what.
Finally, the really biggest surprise for me was the braking. In this respect the car is like your MX-5 - you can leave the braking very late and I often gained most in outbraking opponents into slow corners (1st and 3rd at GVS, Rettifilo at Monza, Degner, Hairpin and Casio at Suzuka). I am not sure this is historically completely accurate but sure makes for a very effective machine.
If I recall correctly, in real life the car's direct predecessor (KGPC10) used the 'late braking throttle prod' technique as well to allow for overcoming the basic understeery balance (apparently more of an issue there than with this car) in racing.
Overall a really pleasant historical car, which is fast enough to embarass much newer machinery over a variety of circuits, and is both easy to drive yet takes concentration to get the most out of. Of the three circuits, Suzuka was most of a challenge - on the other two I would be first over the course of the first lap already (in Monza within the first sector). But beating a '02 NSX Type R, various Evos and Scoobys and Z cars with a machine from 1973, which at the end of the day has less power than most of the opponents, is a pretty special reward in its own right.
Finally, I suppose it works best on flowing circuits, those which are not too bumpy, and the odd high speed braking corner will help its competitiveness, too.