For easy lighting

The number they'd need for gasoline is 1203, one of the few i have memorized. If you ever see a number on a truck, you can look it up on a hazmat number lookup site and it'll tell you what it's hauling. Usually it's gas, diesel, or propane, but sometimes it's something more fun

Edit: i saw a truck with the number 1824 on it, looked it up, and it's a Sodium Hydroxide solution

Probably corners very badly with the Center of Mass being moves up so high

There's no way the roof rack is rated for that much weight (let alone sloshing around).

The baffles are on the road outside the tank

Should there be? Who knows. Are there? Who knows.

Same speed = same RPM, regardless of load / air resistance. Unless they have to drive in a lower gear to make it work, but I doubt that

Given the color it could be used cooking oil for a biodiesel conversion. But outside of cost saving from fuel ubiquity, none of it is an improvement for anything.

No benefit, its just a gag