Well, I don't know about the others, but I do know for a fact that although Applejack "jacked" her car and semi, she got her truck from Hasbro. Weird cardboard cutout of Twilight Sparkle in the back and all.
yeah the car is designed for grip on the road. the side mirrors funnel the air in to the air intake vents on the sides. plus they made the car out of aluminum but scraped it cause it was to heavy and re-did it using carbon fiber. it took them nine years to complete it