I found an interesting glitch during my first playthrough, and despite believing that there is a high chance that is is well known and documented, but I'll explain it just in case.
When I was playing the car levels, I was called to do something, so I paused the game. When I came back, my car got launched forward at ridiculous speeds into the air.
I tested it more, and it sem that, when the car is in motion, pausing doesnt stop it's momentum, and it stockpiles until you let go. Depending on how long you pause, it can go from speed boost to launching you into the stratosphere.
I've also found that is works similarly on the horse which jumps before running, so I've figured out how it works. Whenever an object continues moving on its own in a line without you adding anything(car or horse) pausing the game while they are in motion pauses their movement but not their speed, which increases the more that the game is paused. Sadly, it only works on objects that move on their own, and doesnt count when you are on ice.
By the way, the car and horse tend to get launched differently. First off, the car stockpiles speed much more quickly(probably because it itself is faster) and that the car gets launched at more of and diagonal up+forward angle, while the horse moves mostly forward
this has been found in many first playthroughs by many people and has been used in wrs for years https://www.speedrun.com/whatthegolf/forums/1dxb1