Wellll I think it's about time someone makes a guide. Please note that these are just my own thoughts from my own findings. If you think you've found something that's better then stick with that! The game's pretty unoptimized so there are plenty of improvements to be made I'm sure, so try EVERYTHING!

=====Cars listed from fastest to slowest:===== Bullet Grinder/Blockhead (I think they're REALLY close but the Grinder deals better with debris) Blocker Pepper

=====Beginning the Speedrun:===== After purchasing the Bullet, if that's the car you would like to choose, you'll be left with $0. This is... unfortunate to say the least, but fear not! Completing the first whole split without an upgrade is not a run ender!

Purchasing an upgrade after buying something like the Grinder, which leaves you with $500, will make the time to select the first race around 10 seconds. Skipping the upgrades and immediately heading to the first race will take only about 4 seconds. This results in the first split being roughly the same no matter which route you take.

=====Brad's Pit Crash===== I'll recommend selecting Brad's Pit Crash as your first race. Reason being is that your car has very little upgrades, if any at all, and is still very slow. Because of this, you want to have this "version" of your car to have as little track time as possible. The longer you drive a slower car, the slower your speedrun will be.

=====First Upgrade & the Glitch===== Upgrades in this game are funny. In the 1.0 version of the game that is purchased on Steam, there happens to be a glitch that allows for the duplication of upgrades to their highest potential.

To use this glitch, simply purchase any upgrade in the "Tuning" menu. Then back out to the "Garage" menu screen. Now select "Go Race". Once in the "Select Class" menu, back out to the "Garage" again. With this, the upgrade to your car that you purchased should have stacked 1 more version of itself onto the car. For every "Garage" selection you make this process will repeat. You can see this in the video linked here.

In the video we can see that the upgrade that was purchased increased the HP of the car by 6hp, going from 112hp to 118hp. When I backed out, went to "Go Race", backed out to the "Garage", and then selected "Tuning" again, notice that two "Garage" selections were made, thus making the HP go up by another 12hp to 130hp. Then it continued to go up each time I selected tuning until it maxed out at 190hp.

The tuning glitch doesn't stop with HP related upgrades though. Flywheels, tires, suspension, etc. all stack on top of each other.

Now that we know how to do the glitch, I'll tell you what I usually do. In Bronze, I usually purchase the following upgrades:

Engine: Carburetor & Manifold level 1

Drivetrain: Clutch Level 1 Flywheel Level 1

Suspension: Shocks Level 1

Tires: Tires & Brakes Level 1

After racing on Brad's Pit Crash, you can usually do enough damage to the environment to gain around $1400. That is enough to purchase all of these items. With the Carburetor & Manifold, you'll have to Glitch Stack the Bullet 12 times to max it out.

=====It's Free Real Estate===== After Brad's Pit Crash and purchasing all the upgrades you want, the tracks you pick are up to you. You have the fastest car you can possibly have after only the first race so the order from now on is up to you!