How many points are good enough? This is somewhat subjective, but I'll try to give some numbers for comparison. Also, the B-spec level isn't as good of a measure as skill, so let's assume that the battle skill and course skill are almost the same, and their score matches the % of B-spec level.
[Level/Machine/Course/Battle] Examples: 5500/66/55/55 (55%), 7700/88/77/77 (77%).
30% - Poor: Don't trust the B-driver unattended.
50% - Fair: Probably safe in an endurance race with a powerful car.
70% - Good: Can win the F1 Seiries.
85% - Great: Can win Opel races rated at 200 A-spec points.
99% - Outstanding: Expect to control every race.
100% - Outstanding: Still makes mistakes on tricky turns if the pace is too high or the car isn't properly tuned. 10000 B-spec points is mostly a matter of statistics and point collection.
7000 points is about average if you use B-spec a lot during normal play, but you didn't follow any guides. 8500 points is pretty good for normal play and is reported by people who make the B-spec driver work at winning. Once the skills get over about 80%, their influence on driving is much more noticable. The improvement to passing ability is dramatic.
To build B-spec skill gradually during normal play, I suggest racing and tuning every new car won on Nurburgring until the machine skill is maxed out. Then race your new cars on tracks that aren't used as often for that class of car. It shouldn't take long to get a B-driver with 80% or better skill that can be trusted to win almost any race.
[Level/Machine/Course/Battle] Examples: 5500/66/55/55 (55%), 7700/88/77/77 (77%).
30% - Poor: Don't trust the B-driver unattended.
50% - Fair: Probably safe in an endurance race with a powerful car.
70% - Good: Can win the F1 Seiries.
85% - Great: Can win Opel races rated at 200 A-spec points.
99% - Outstanding: Expect to control every race.
100% - Outstanding: Still makes mistakes on tricky turns if the pace is too high or the car isn't properly tuned. 10000 B-spec points is mostly a matter of statistics and point collection.
7000 points is about average if you use B-spec a lot during normal play, but you didn't follow any guides. 8500 points is pretty good for normal play and is reported by people who make the B-spec driver work at winning. Once the skills get over about 80%, their influence on driving is much more noticable. The improvement to passing ability is dramatic.
To build B-spec skill gradually during normal play, I suggest racing and tuning every new car won on Nurburgring until the machine skill is maxed out. Then race your new cars on tracks that aren't used as often for that class of car. It shouldn't take long to get a B-driver with 80% or better skill that can be trusted to win almost any race.