I did 0-50 cuz only 6 ATVs made it to 60 mph which makes me wonder how you got a top speed of 68 for the racing ATVs.

To see those top speeds just go to free ride and find somewhere where it’s completely flat, no incline/decline and no bumps. You’ll see that the ATVs will all speed up steadily to hit their effective top speed and then it will basically stop and only slowly increment to the top speeds I listed.

Which just reminded me, that’s all the evidence right there that tuning doesn’t do anything, or else the top speed would change wouldn’t it? I mean I’m not trying to suggest this as a theory, I know for a fact that it doesn’t do anything when you tune the acceleration and top speed, and I’m at least 90% certain it doesn’t do anything for the other categories either.

I’m going to check your link a little later, but just pick any ATV and do what you did for the spreadsheet. Do it once with tuning set all the way to acceleration and record it, then do it again with tuning set all the way to max speed, then play the two back side by side.

See I did go somewhere with no bumps. Every ATV reached a certain top speed during the test and that's where they capped out. It wasn't like they were still getting faster and they just reached the end. They just stopped going faster.

That’s why I call it the “effective top speed” because that’s what’s mostly relevant, it takes too long to gain more relative to what any track in the game allows. But the actual top speeds are indeed what I listed.