chubbystickfigure and I did some extensive testing on the Mystery Racer and overall speed of the game. First, all characters have their own stats: Tarquin is +1 Top Speed and +1 Cornering, Olaf is +1 Top Speed, Cornering, Acceleration, and Jumping. Also, if a character has a +1 speed stat, it is the exact same speed increase as 1 engine upgrade, or 1 car upgrade. But, getting an engine or car upgrade also increases acceleration by +1 as well. So Snake (+1 Top Speed +1 Acceleration) with a Marauder has exactly the same speed and acceleration rate as Katrina (+1 Cornering +1 Jumping) with the Air Blade. By comparing the Mystery Racer's cornering, jumping, and acceleration against the other characters, I figured out that Mystery Racer has: +0 Acceleration +11 Top Speed +0 Jumping +0 Cornering

Figuring out the top speed was a little difficult. I created a password with the Mystery Racer that had a Marauder with no engine upgrades, (car has +0 Top Speed), and compared its speed against Tarquin (+1 Top Speed) with the Havac (3 cars higher than the Marauder, so +3 Top Speed) and the Atlas Power Boss engine (+3 Top Speed.). So Tarquin with his car had a total of +7 Top Speed, while the Mystery Racer's speed came only from his character stats, not his car or upgrades. Even with all this, Mystery Racer was significantly faster. Next, I created a 2P password with 2 Tarquins, one with the Havac and Atlas Power Boss, another with Maruader and default engine. Then, I continually raced the 2 against each other, comparing their speed, and upgrading the second Tarquin's engine after each race until the speed difference was the same as the speed difference between Mystery Racer with Marauder and Tarquin with a maxed out Havac. The speed difference matched when player 2 Tarquin had Marauder with Super Charger (second to last engine), so a total of +3 Top Speed, whereas the other Tarquin had a maxed out Havac at +7 Top Speed. The speed difference between these two is 4, (7-3=4 )and it looked like the same apparent speed difference that was between Mystery Racer with Marauder and Tarquin with maxed out Havac, which means that the Mystery Racer's character stats must be +4 Top Speed higher than Tarquin with maxed out Havac, which puts the Mystery Racer at +11 Top Speed.

Next we looked into the effects of lightning nitros (rocket accelerators). We found that they don't actually increase a characters speed or acceleration, they just temporarily set their speed to a certain value. For example, Olaf with Air Blade with the first engine has +2 Top speed, a rocket accelerator is +8 for example (I don't actually know the value of it's speed), so instead of increasin'g Olaf's speed by +8, it just sets his speed to +8. Since the Mystery Racer's top speed is already much faster than this, USING LIGHTNING NITROS ACTUALLY SLOWS DOWN THE MYSTERY RACER SIGNIFICANTLY. Yes you read that correctly, the Mystery Racer is FASTER THAN A ROCKET. We tested this multiple times going side-by-side, and It was a very large speed reduction.

However, Mystery racer has +0 acceleration and +0 cornering, so using rocket accelerators at the start of a race, or after you spin out, blow up, or anything that puts you at almost a dead stop, does really help. Since the Mystery Racer has a low acceleration, using a rocket accelerator when you are already moving really slow (or not at all) can help get you up to top speed much quicker. However this is only effective if you use the rocket accelerator within about less than a 1/2 second after you start accelerating, if you wait any longer than that, or even if you wait until you are already at top speed, the speed reduction of the rocket accelerator kicks in and it is no longer advantageous.

Next we tested using the rocket accelerator going around corners and up hills. Since it slows you down when you are already going, it doesn't help you to get over a hill any faster. It initially helps with a tiny kick, but after that the speed reduction slows you down and you immediately lose any time you saved and more. Going around corners seams to be up to prefference. Using the rocket accelerator does slow you down, but it also helps you to make a tighter corner, so thus the amount of ground you cover in a race is slightly lower, so it balances out.

Then we tested warp points, these are still good, always. From what we could tell, every time under every condition, whether we were just starting to accelerate, going up a hill, or already at top speed, hitting a warp point always gave us a small temporary speed boost.