Go into your Achievements screen and check what you need. Try purchasing cars such as three Fords, three Aston-Martins, etc. You will know what cars you need by looking in the purchases area of your achievements. To gain enough money to buy the cars, keep repeating the 170 mph race. Once you have completed enough achievements to become a champion, repeat the Alfa Challenge in the Competezione car that should cost you nothing. You will receive $75,000 for each win.

Go to the bottom of the map by the crater. There is a speed challenge there that awards $40,000. A C-Class car is required (TVR Sagaris recommended). You can do it in about 1:30 to 2 minutes and get $40,000, which results in about $1,200,000 after one hour.

Once you get to "Champion" rank, complete the Tour Of The Island race if you have not already done so. After completing the Tour Of The Island race, you will get the Alfa Romeo 8c Competizione. There is a race on the main highway called "Alfa Romeo Day". Every car in this race will be an F class Alfa Romeo while you will have the C class Alfa Romeo. The race is about 2.8 miles long on a near straight-a-way. You will earn $75,000 for the race.

Once you are at "Champion" rank, do the "Alfa Romeo Day" race. Use the Alfa Romeo 8c Competizione. Everyone else will have different slower cars. The race is on the highway with no cars and is only 2.8 miles long. It is worth $75,000. Keep repeating this for easy money.

Find the highway and go to a spot near but not too close to an intersection. Find a racer and get them to have a Instant Challenge with you. Set the finish line just behind the start line on the opposite side of the highway. Once the race starts immediately turn over the center of the highway and drive past the finish line. Do this five or ten times then do a race that is worth about $20,000. You will get a lot of money for the win. Note: This does not always work.

Once you reach the Expert level, there is an easy race called "Lucky Day". It only lasts about two minutes and results in $40,000 every time. Try using the Kawasaki Ninja ($14,000) with the stage 3 tuning package ($25,000).