This is always something I’ve wondered about. We’ve seen cars, planes, submarines, boats, helicopters, tractors, and even what forklifts look like in the world of Cars, now what about Trains? So far we’ve seen one freight engine 
but what about Steam Engines?
You know, like the one that appeared in Toy Story 3? We all know John Lasseter is a huge fan of trains so how come we’ve never seen them any in the Cars world before- what do they look like?
Seeing more trains would be nice, along with more boats, planes, ect.
Come to think of it, why are Cars the most dominant species? Trains and boats, they probably have low populations because they have to stick to a certain environment (water, rails)
But Planes, they are clearly the most superior race, due to the fact that they can be wherever they want. (Cars are all stuck to the ground)
What about Ambibious Assault vehicles or Hovercrafts?
Personally, I always thought one of the reasons why Trains haven’t really shown up in their world yet is because they would look too much like Thomas.
well, they’ll be a train in cars 2. His name is Stephenson. Hes a spy train who works for McMissile.
And don’t forget Siddley the plane! 
I’m not too interested in trains as in characters in the movie. I wonder how many we will see in the sequel.
Personally, I would LOVE a Cars spin-off called Locomotives, but don’t count on it happening.
See this Digimon?
or this one:
There are many others. Trains in the Cars world won’t look anything like Thomas the Tank Engine…but they will look like Trailmon.