Power Units refers to the self-propelled vehicles in a carrier's fleet — tractors, straight trucks, and similar equipment capable of moving under their own power — as distinct from trailers, which have no engine and must be pulled. FMCSA's Company Census data reports the total number of power units a carrier operates (owned, term-leased, and trip-leased combined), and this figure is one of the most-used proxies for a carrier's size, since it roughly correlates with hauling capacity regardless of exactly how many trailers or drivers it also runs. A carrier reporting zero power units on its most recent MCS-150 filing is a strong signal that it's not actively operating trucks — filtering out zero-power-unit entities is one of the most effective ways to separate real, operating trucking companies from carriers, brokers, and other registrants with no equipment on file. FMCSA also derives a letter-coded Fleet Size classification from this number for quick categorization. Power unit counts are self-reported on the MCS-150 and only updated biennially, so a fast-growing or shrinking carrier's on-file count can lag its actual current fleet.
A carrier listing 6 power units and 7 drivers is a small operation — likely an owner-operator or small fleet, not a large trucking company.
Shown as 'Power units' in the Fleet Profile section, alongside the owned/leased breakdown by equipment type, on every carrier profile.