Hidden Trophies
A few hidden trophies can be earned while racing in "Gran Turismo 5." The Endurance trophy is earned when you complete your first Endurance series of events and the Red Bull X1 Challenge trophy is earned when the event of the same name is completed. The Watch Falling Objects trophy is earned by damaging your car to the point where pieces of it fall off, while the Rollover trophy is earned by causing your car to flip over and land back on its wheels.
Refresh Used Car Dealership Quickly
The used car dealership can be a source of great cars at bargain prices, such as the Formula GT car. However, the dealership only refreshes itself once every in-game day. A day passes when an event is completed. To quickly make a day pass, load up any license test. Once the test is loaded, skip to the next test using the in-game menu and then exit the mode. The used car dealership will have now restocked a portion of its cars for sale.
Earn Credits Quickly
In "Gran Turismo 5," credits are the currency used in the game to purchase cars and are unlocked by winning races. To earn credits quickly, play A-Spec races until you reach Level 23, giving you access to cars that can easily beat lower tier races. Return to B-Spec races with any of the cars you just earned; you will easily be able to pull out in front of the other racers and quickly win the race. Repeat this to amass a large number of credits in a short time.
Change Oil/Birthday Car
Changing the oil in your new car always results in a boost to horsepower, which allows your car to reach faster speeds. You should do this immediately with each new car you receive, including your birthday car. When you play "Gran Turismo 5" on your birthday, you are awarded a free car when you first enter GT mode. The car you are awarded varies based on the year you were born.