It takes approx. two hours to load/unload a fully occupied Auto Train at Lorton or Sanford. But that's assuming 200 cars or better and 500 - 600 passengers.
A smaller operation, e.g. 100 cars, would go a lot faster. Also, the process could go faster if there were more loading tracks and more people driving cars on and off the railcars.
My vision for expansion of Auto Train service would not be dedicated trains, but add-ons to existing long-distance trains. For example, the westbound SW Chief could add A-T cars at Chicago (or suburbs) (gateway to Milwaukee, Detroit, Cleveland, Indianapolis, Columbus and Cincinnati) and Kansas City (Gateway to St. Louis, Omaha, Des Moines and Twin Cities) and drop them at Flagstaff (gateway to Phoenix, Grand Canyon and Las Vegas) and San Bernardino (gateway to LA, San Diego and the rest of California). Passengers would ride in coaches and sleeping cars running through from Chicago to Los Angeles.
Operationally, coming out of Chicago (or suburban stop) would be blocked:
Chicago - San Bernardino
Chicago - Flagstaff
Auto carriers originating at Kansas City would be blocked:
Kansas City - San Bernardino
Kansas City - Flagstaff
and inserted between the two blocks that originated at Chicago so that the auto carrier section of the train would now be blocked:
Chicago - San Bernardino
Kansas City - San Bernardino
Kansas City - Flagstaff
Chicago - Flagstaff
The auto carriers destined for Flagstaff and San Bernardino would be cut off when the reach their respective stations. The switching moves are relatively straight-forward and should take 15 - 20 minutes per station, adding 1:00 to 1:20 in running time.
What is the revenue potential? Lets assume the following:
Autos per auto carrier = 12
Passengers per auto = 2
Auto carriers Chicago - San Bernardino = 2
Auto carriers Chicago - Flagstaff = 2
Auto carriers Kansas City San Bernardino = 1
Auto carriers Kansas City Flagstaff = 1
6 auto carriers
72 autos
144 passengers
At peak times, this load would probably require one additional coach and one - two additional sleepers.