I managed to get it yesterday in the Toyota 7, though not entirely without issues.
The key point to the 7 is fitting the high RPM turbo and use a pretty close range gear ratio - I set it up for 260km/h.
I'd tried with mid-range turbo and varying gear ratios, but the 7 revs so fast that high RPM is the only way to go. It'll really boost acceleration a lot.
As many other threads and posts have mentioned, the grid is very important too. 2Js are the only real threat, so try to minimise the amount of them to 1. Another point is that it gets very difficult to pull off a 2J is starting in pole position, so try to get them down the grid a bit. They don't need to be behind you, but a bit down helps a lot.
Lastly, where possible, try not to overtake on the straight through the tunnel, because depending on what car you're trying to overtake, the straight may not be long enough to actually get past, meaning Bob will get stuck on the inside of a car, trying to cut the chicane short, leading him to ram headfirst into the left hand barrier. That's disastrous as he'll generally duly wait for everyone to pass, then slowly reverse and eventually start moving forward again. If it happens, you may as well abandon that try.
Try to continously press Decrease Pace as you hit the hairpins if you're worried you won't pass the car on the tunnel straight. Should keep Bob in check. And definately don't try to pass the 2J there!
Best place to pass cars (since the 7 isn't a rocket through the corners) is the first corner and the straight after it, as well as on the outside of long 2nd corner, inside on the 3rd corner (especially if overtaking one of the sliding GT40s) and finally in the 4th corner (the first hairpin). After the chicane it's damn near impossible.
And watch out for miserable AIs. They'll sometimes pull off the trick in the chicane too and cut it short, leading to them getting stuck on the inside barrier. Especially the 2J and to an extent the 2D. Sometimes it's unavoidable due to the layout of the grid. Some combinations of cars just seem to force that situation. If it happens again and again, get a new grid.
I hope that helps, it's definately beatable.