Couldn’t you technically make infinite speed by putting a car in a vacuum chamber? Since top speed it made by the amount of force it takes until power and wind balance couldn’t you just get rid of that factor entirely?

No

Explanation:

For infinite speed to be achevied, one must have no sink of energy to spend. The source of entropy in this example, is the tires hitting the surface, producing heat and friction. Not to mention that you'd still need fuel to start the car, and an infinite tunnel or track, which would be impossible and speed up to process of energy loss through entropy quicker.

a.) travels faster in solids because the particles are closer together.

air is a gas water is a liquid