All golds is possible.........but only if you're commited. You can't really give out a real strategy for getting all golds, as it depends more on skill. But here are a few general tips anyway:
1) Be patient. You'll never get all golds by attempting each test for only about 15 minutes at a time. Some tests may literally take you over an hour to finally get gold on, so its not a quick process.
2) Study the demo. I recommend changing to the view that you will be driving from (1st person or 3rd person). Turn on the throttle, speed, and turning meters so you can see where the demo car breaks, turns in, begins accelarating, and what speed the car is traveling at a particular portion of the test. You can even try pretending that you're driving the demo car. Then you can see what the demo car is doing different from what you are doing and adjust accordingly.
3) Use the ghost car. This way you can improve on what portions of the test you make errors on. You don't have to immediately start the test over if you fall behind your ghost car because you may be able to make up time later. However, its probably best to start over on short tests or tests where its vital to keep your speed up. Turn the ghost off for a while if you find it is causing a distraction, but turn it back on if you see that your lap times aren't improving w/o it.
4) NEVER scrape walls, slide around corners, or have to make any major countersteering adjustments. Even though it may seem like you scraped the wall lightly, doing these almost all the time ruin a chance at getting gold.
5) Take breaks. Its probably best not to sit down and attempt a test for 2 straight hours. Take some breaks in between sessions. Go fix a sandwich, go outside and get some fresh air, or go walk the dog. This also helps to eliminate frustration. You are pretty much guaranteed to NOT get gold if you keep trying while frustrated, and it only worsens when you can't better your lap times. Remember, frustration tends to make sloppy drivers

Frustration can lead to you suddenly turning the PS2 off in an outrage, causing you to lose any data or having to redo other license tests that you worked oh-so hard on for 2 hours to finally get gold on. This can lead to more frustration, like damaging the PS2 or TV, furniture, or other humans. This can lead to trouble with parents or other relatives, which in turn can lead to (I think you get the point

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