I'm not American and I often see captchas that ask about "cars" or "trucks". And they use similar images. I sometimes don't pass through those. My question is, when I see a truck and I'm being asked to select all cars, should I select the truck or not? For me a truck is a car. Is it not one?
The way I learned it, a "car" is any roofed 4+ wheeled vehicle up to van and SUV size (yeah, more Americanisms). Pickup trucks and larger are "trucks".