It will be oversized if your vehicle is a heavy truck or some other vehicle where some equipment is fixed to it. If the car is taller than the average, it would be oversized. In most cases, weight is not necessarily a factor.
The auto transport dealer you want to employ would not be able to quickly locate a carrier to initially transport your oversized vehicle. They are not going to be able to communicate with the carriers they would usually call. This results that the dispatch method can be much slower. Dealers also partner with carriers with which they have partnered in the past, contributing to a quicker phase but high pricing.