A tractor-trailer leaves a Chrysler assembly plant in Illinois.

A load of cars leaves a Chrysler assembly plant in Belvidere, Ill. Car makers log hundreds of millions of miles on the road deliver automobiles to dealerships across the country.

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Going by Truck

Every new vehicle at some point in its delivery to the dealership is carried by truck transport. It's not hard for automakers to roll up the mileage. Toyota alone averages 45 million total highway miles annually to deliver 2 million vehicles to nearly 1,500 Toyota and Lexus dealers across the country [source: Nelson].

Today's tractor-trailer auto transporters can carry up to 12 vehicles. The rigs are designed so that the tractor can support up to four vehicles and eight vehicles are placed on the double-deck trailer. The tractor-trailer rigs utilize hydraulically operated ramps. Each ramp can be lowered or raised to provide a smooth approach for loading or to clear vehicles under it when the trailer is fully loaded. The ramps can also be tilted to maximize the available space by tucking the end of one vehicle under another [source: Becker and Stone].

The transport driver is responsible for loading and unloading the rig. This operation has been compared to solving a 3D puzzle because of the time, vehicle size and scheduling issues that have to be juggled. Obviously, the first car loaded can't be the first car delivered, or else the entire trailer has to be unloaded. Some cars are backed onto the trailer while others are driven in nose first to maximize space or meet overhang requirements. Larger vehicles are usually on the top level. An experienced driver can load and secure a trailer of familiar, similar-sized vehicles in about 90 minutes. A load of different-sized vehicles can take up four hours [sources: Becker and Stone].

For the average motorist traveling behind an open-trailer auto transporter, the obvious fear is a vehicle falling off onto the highway. Officials say such an incident is extremely rare because each vehicle is secured at four locations. Chains and straps are used to secure vehicles to the trailer.

Most cars are manufactured with specific tie-down holes in the chassis or frame. Chains with specialized hooks to fit those holes are ratcheted tight to secure the vehicles to the transport trailer. The transporters even have specific requirements for the mounting angle of the chain from the vehicle to the trailer. Luxury and exotic automakers require less intrusive methods. The strap system utilizes high-strength straps that are positioned over each tire and tightened to the trailer, eliminating scratches or dents to the vehicle chassis.

Both methods are very secure. Transporters that have flipped in an accident have been known not to lose a single vehicle.

Jump into the next section to learn how to transport a vehicle --or hire someone to do it for you.