The F3 - note thick wheels, rubber-tired wheels at rear. To open this, you must squeeze the steps at the lower right and left of the car, then raise the shell. Next, slide it off the rear tab. The instructions didn't show that.
Here is the inside. Right and left tall tabs in front of batter compartment are attached to the steps. Motor is in rear.
Track sections connect via the loop. Each is a little over 5" long. It takes 16 curves to make a complete circle.
Note the undercarriages of cars. Passenger cars and diesels have wheels that are silver-colored, and feature very wide, thick flanges.
A close-up of passenger car / diesel type wheel set with extra-large flanges. Modelers seeking a more scale appearance would have to replace these with TT or HOn3 wheel sets.
Freight trucks and wheels look pretty good, insofar as realism.