Compared to most console racing games of its time, World GP was much more difficult. The circuits were accurately depicted as having both sharp and wide turns, thus requiring players to slow down to certain speeds for corners, instead of most arcade-style games, which allowed players to unrealistically take turns flat-out. Gear shifting was also required for three of the cars (and notably for 8 of the 9 levels of the game), and some courses required dozens of gear changes per lap. Tire wear increased as the races went on, and players would be required to pit for tires at least once during each race to remain competitive.
Button assignments were traditional and simple.
"Left" and "Right" were used for steering. These two buttons were tapped singly rather than held down during turns. In cornering, the cars made predetermined angles of curvature depending upon the number of taps.
"Up" and "Down" were used for upshifting and downshifting, respectively.
"A" button and "B" button were used for the accelerator and brake, respectively
Quickly tapping the "A" button during pit stops increased the speed of the pit crew
Simultaneously holding down "A" button and "B" button held the car's speed, aiding the player in cornering
A trick for getting through some of the higher-speed tight turns is to continue to drive straight, flat out into the turn, and lock the brakes as you enter the grass. This causes the car to slide through the grass, and follow the line of the track. Once the car re-enters the track after the turn, you get back on the gas, and keep on racing. It adds an excitingly fun an explorative skill element to the race, as you must time your braking so as to only skid while on the grass, otherwise you decelerate very quickly by braking on the road. It is also challenging to see where this technique aids/hampers your time.
When multiple cars were on the track, the game featured no direct interaction between vehicles. All of the competitors' machines behaved in a ghost-like manner, and could be driven through and occupy the same space as others. Cars were unable to spin others out, and could not directly impede their progress.
Nearly every screen in the entire game featured a short-looped, repeating soundtrack. Unlike most racing games, however, there was no music played while actually driving.
Source: Wikipedia, "Michael Andretti's World GP", available under the CC-BY-SA License.