the bar gets below half, you should win this race by (literally) a mile.

Guide to Gran Turismo 5's Extreme Series, covering easy, middle, and hard races like Schwarzwald League B and European Championship.

The Easy Tier:

The "Like The Wind," "Super GT," and "Dream Car Championship" events can all be completed using the Red Bull car.

The Middle Tier:

These three races are manageable with the correct car and setup.

1. Schwarzwald League B: Use the Audi Lemans Quattro '03 (obtained from winning the European Championship in A-Spec). Purchase all available mods and increase HP to approximately 750. In the tuning menu, under the Drivetrain tab, buy a Torque Sensing Center Differential and adjust it to 10/90 instead of 50/50. The first race is at Cape Ring; you can take the lead by the first turn, and a decent lap will grant a 10-second lead. The next race is at the Nurburgring; if you are familiar with the track, you should have no issues. For B-Spec, equip Sports Soft tires and maintain the existing setup. The Cape Ring race may allow you to set the controller down, but consider pacing your AI driver (NPC (non-player character — anyone the game controls, not you)) once per lap. For the Nurburgring, you should be in first place within the first minute, even with the AI's reluctance to overtake. The remaining races are in the Grand Driving Simulator (GDS), which may not require active supervision.
2. European Championship: The Bugatti Veyron, won from the Professional Series of A-Spec in the Gran Turismo World Championship, is the recommended car. Mod (a community-made modification that changes the game) it to around 1100HP to dominate the series, potentially lapping opponents in A-Spec. In B-Spec, you can leave the AI driver unattended due to the significant speed advantage. You may need to create an additional driver as two are required for the first time. You might also notice pit stop options are enabled for the first time; these are not necessary for these races but will become important soon.
3. German Touring Car Championship: This race has a limited field of 13 qualifying cars. The IS Racing Concept '08, available for purchase at the Lexus dealership, is a suitable option. With modifications, it will exceed 750HP. In A-Spec, you should not encounter major problems, as better tires significantly improve performance. However, the car tends to spin when exiting corners. To mitigate this, consider enabling Skid Recovery Force in your Driving Options. For B-Spec, you will likely need to monitor the races closely. While you are faster than the competition, the margin is small. Ensure your General Driving Strategy (GDS) is set appropriately.

The Hard Tier:

These three events are the most challenging in both A-Spec and B-Spec, surpassing even the Endurance races. They are listed from easiest to hardest.