^^^You sort of answered your own question.
Most manufactures make a train design that has 1 wheel assembly per car with the exception of the front car which has the additional wheel assembly up front.
Millennium Force Front car w/ 2 sets of wheel assemblies, 1 of which being a pilot car:
Non-Front cars with 1 set of wheel assemblies:
Source
Arrows use "zero-cars." Same principal, just reversed.
Source: TPR Park Index
Source