The first of Ford's all-new 2017 Super Duty pickups are selling very quickly, and at very strong prices. Image source: Ford Motor Company.

Ford Motor Company (F 0.47%) said that its U.S. sales fell 8% in September, as an expected year-over-year drop in rental-fleet deliveries exacerbated a 4% decline in retail sales. 

By the numbers: Trucks still strong. Cars -- not so much

Ford's result was in line with estimates by analysts, who had foreseen a significant year-over-year drop for two reasons. First, Ford's sales to rental-car fleets were elevated in late 2015 and early 2016, and the company had said that it expected lower rental-fleet sales through the remainder of this year. Second, September 2015 was a terrific month for Ford's U.S. sales: It's a tough comp. 

In that light, Ford's sales totals aren't quite as worrisome as the headline number might suggest, particularly with respect to its profit powerhouse, full-size pickups. Sales of Ford's F-Series pickups were down 2.6% from a tremendous year-ago result, but still very strong at 67,809 sold. 

SUVs were more of a mixed bag. Sales of Ford-brand SUVs were down 3.2% as a group, with the Escape and Explorer both down about 12%. But Ford sales chief Mark LaNeve noted that the average transaction price (ATP) for the Escape rose $500 in September, while the ATPs for the compact SUV segment as a whole were down $360. He attributed the Escape's pricing strength to a strong "mix" of well-optioned 2017 models. 

Like most rivals, Ford's sedan models have had a tough 2016. Sales for the group were down 22.5% in September, with all models suffering double-digit percentage declines. The drop in rental-fleet sales has hurt totals for models like the Fusion, which continues to do well at retail; but overall, the group is suffering from an ongoing market shift away from sedans and toward trucks and SUVs.

The all-new 2017 Lincoln Continental sedan has also begun arriving at dealers. Image source: Ford Motor Company.

On a somewhat brighter note, U.S. sales at Ford's luxury Lincoln brand were up 1.3% in September, as Ford's effort to revitalize the old brand continues to make slow progress. The midsize MKX crossover SUV was the star, with sales up 8.7%. Also helping: The first examples of the all-new Lincoln Continental began arriving at dealers in September -- 775 of the big sedans were sold last month. 

What it means for Ford and its investors

For Ford investors, there are a few pieces (relatively) of good news in the September sales report.

First, the growth in Ford's overall average transaction price continues to outpace that of the industry. Ford's ATP rose $1,100 in September from a year ago, versus a $400 gain for the overall industry, the company said. 

Second, Ford's use of incentives remains under control. TrueCar estimates that Ford's per-vehicle incentive spending as a percentage of ATP was 11.7% in September. That's up from 10.5% a year ago, but at the same level we saw in August. Among pickup competitors, General Motors' (GM 4.37%) spending was comparable at 11.3% of its ATP, while Fiat Chrysler Automobiles' (FCAU) was significantly higher at 13%.

Third, Ford's latest new product is showing early signs of being a highly profitable hit. Inventories of its all-new 2017 Super Duty pickups are still building, but the trucks are spending an average of just 13 days on dealer lots (anything under 30 days is a very quick sales pace). Better yet, LaNeve noted that retail buyers are choosing highly optioned models; the 2017 Super Duty's ATP in September was a whopping $62,000, he said.

The upshot: Trends still suggest a profitable quarter

Ford has warned that its profits will dip because of increased spending. But even with overall sales down somewhat, the trends in its U.S. sales numbers suggest that -- at least in North America -- the Blue Oval is still on track for good profit margins.