Soooo, if you were riding him, would that be a Grapple check, an Athletics check, a Land Vehicle check, or improvised weapon check?

Yes

Wait. Does Buggy have PIG TAILS? Is his hat open at the top and his hair is spilling out on either side? I thought those were feathers the whole time! I don't think I'll be able to take buggy seriously anymore now that I know this. It's just too silly.

Oda actually covered this. Yes. That is buggy's hair as pigtails flopped over the edges of his hat like tassels.

You could take him seriously before?

Don't take him lightly. Clowns are from space.

Are you crazy? Everyone knows the only thing in space is moon moles.

Dammit he knows!

Dammit, I know!

Dammit, They Know!

Dammit, you know?

I'm from Georgia!

with this lenght, i think we can call theses twintails.

Where in the blue hell did he get rubber tires and metal axles from? I don't recall cars being a thing in OP.....

Great Shades of Elvis! Buggy's been to Full Metal Alchemist!!!!

I think it was this one car that one time.

You'll see another one shortly, but I won't spoil it.

I'm almost afraid to ask what he uses for propulsion.

I think it was explosives, actually.

The Bara Bara no mi allows the user to fly.., but not their feet.

A valid workaround is to use that fly speed to propel something, and have that thing support his feet. Like, have a person on your back and have them hold your feet.

So this could be an attempt of Buggy to use his fly speed productively.