The type of carrier you choose affects the price greatly as open and enclosed carries offer different services. Open carriers are the most common and are in the highest demand as they cost less to maintain and can carry more cars per trip, however open carriers don't offer maximum protection to cars while on transit as they are exposed to the environment and road conditions. Enclosed carriers on the other hand are more expensive to maintain and carry less cars per trip. The advantage is that enclosed carriers protect cars completely from the environment and road conditions, however this benefit has an extra cost.
Make and model also affect the price greatly as the dimensions and model of a car require different accommodations. Large and heavy cars take up more room than usual and sometimes take up two spaces, causing the driver to take less cars, therefore prices are higher to compensate. Some vehicles are smaller in size however weigh more causing prices to go higher as well. High end luxury cars, sports cars, convertibles and classics are usually taken via enclosed to offer max protection and as mentioned before enclosed carriers are more expensive to hire.
As all industries, car transport is also regulated by season. The highest peaks are during summer and winter. Northern routes specially are affected by the winter season as the heavy snow fall and road conditions cause delays and mechanical issues that can push back schedules. The risks and demand are greater. Summer season also takes a toll on prices as during this time gas prices tend to rise and the demand increases for all routes before winter hits again.
Mileage and location are two factors that go hand in hand, although many people think it is the same thing, unfortunately they are not. Two places can have the same distance and miles, however one can be located 300 miles off route. This fact makes prices to go up as drivers have to make a route out of this one car delivery. Locations such as gated communities or across ferries also raise prices as drivers have to go though tolls and pay extra fees to get through. Passing a 4 wheel car is not the same an 18 wheeler. For this reason it is recommended if possible to meet the driver before these crossing or to a closer area to the main route to avoid the higher cost, in case you are working with a budget.