Only two words for this stage: demolition derby.
5 events, 5 races, all Suzuka. 10 gold for finishing. This can be a tough one, so let's jump in:
Event 1: Cup. Smash the rear windshield of 3 cars with no brake assists, and win the race
Event 2: Endurance. Short track. Exceed 175 mph/282 kph and win the race
Event 3: Hunter. Smash the windshield of the hunted car, and come in first. No brakes.
Event 4: 2 lap cup. Smash rear windshield of FIVE cars and win the race, no brakes.
Event 5: 1 lap cup. Win the race, standard.
Tip 1: For the endurance race, your only chance to hit the speed mark is on the one straightaway. If you find you're close but can't quite get there (and you use brake assists), do this: at the start of the straightaway, pause the game and turn your brake assist all the way off. Full speed ahead and screw the turn - plan to keep going off track and into the wall (then turn assists back on). If that still doesn't get you max speed, you may need to upgrade. Warning: you're better off doing this after you've reached first place: otherwise you may run out of time getting back on the track after hitting the wall.
Tip 2: Don't get carried away smashing windshields from the start. Focus on getting towards the front, then start bashing. Otherwise you risk not being able to catch up to first. Aim at the back corner of the car on an angle, not straight on. The best way to do this is to give the car ahead of you some space, and wait for the next turn. As they slow down and begin to turn, your momentum will take into into their rear, smashing the windshield AND slowing you down enough to not slide off into oblivion. It will take some practice. Sometimes it takes 2 hits, so if the first hit doesn't smash, stay on that car and hit them again at the next turn. There are a lot of turns on this track, so lots of opportunities. BUT, you won't have many laps to get this done in. Most of you will probably not get it the first try. Heck, it took me 4 tries. I suggest practicing with a low-end car before tackling this if you haven't gone off brake assists much. Otherwise you'll be needing to service the Audi after each race or two, which will eat up time and/or gold.
Pics to follow. Good luck!