Ford sold 522,087 F-series trucks in the USA from January to July 2018. If that figure doesn’t stun you, consider that full-line sales of Subaru and Volkswagen were just 382,286 and 365,799 in the same period. Hyundai-Kia’s full line sales were 733,474 — less than Ford F-series plus Ram pickup/chassis cab sales.
In the United States, the F-series is the top seller; #2 is the Silverado (337,341), and #3 is Ram pickups and chassis cabs (273,815). GM also sells pickups under the GMC label, so its lead over Ram is higher than it looks. That is pretty amazing, but we should consider a few things before we pick our jaws off the ground. The first is that truck nameplates aren’t handled like cars are. For trucks, “F-series,” “Silverado,” and “Ram” cover an awful lot of ground. As one example, FCA sells three very similar cars under different names — the Charger, its two-door version (Challenger), and its upscale doppleganger (300). Admittedly, all three registered just 116,873 sales so far this year, but the point is that, if they were pickups, they would be reported as “L-series, 116,783.” As cars, they’re reported on three lines. The Ford F-series includes three distinct designs, the F-150; the F-250 and F-350; and the F-450 and above. Silverado has similar divisions, as does Ram, which goes from 1500 to 5500. The 2500 and 3500 are similar (except for the rear suspension), and the 3500, 4500, and 5500 chassis cabs are similar. Standard and heavy/super duty are different vehicles, launched in different years, but are reported together.
Then there are different cab sizes. Automakers usually sell big and small variants of the same basic design under different labels, but with trucks, they’re just options — regular cab, club cab, quad cab, Megacab (a Ram label). There are also different bed sizes, different lifts, and off-road variants. But they’re all reported on the same line.
There are historical and present reasons for doing that. The historical reason is likely that pickups used to have remarkably low sales, so there wasn’t much desire to list them all separately. The present reason is to have a good placement in the sales wars, especially for Ford, which can always have the best selling “vehicle” in America; but GM and FCA can claim #2 and #3, which would disappear if they started breaking up the sales lines. There are also competitive reasons for not disclosing which versions are selling better, in the hotly contested segment.
In any case, just remember, comparing pickup to car or SUV sales is a bit tough, because there are massive numbers of truck variants, and usually cars and SUVs get different names even for very closely related vehicles.