Ford posts a 6.4% year-over-year gain in July sales in the U.S. on a daily basis, a performance it says was hampered by continued tight inventories on key models.

The auto maker has been plagued all year by low inventories of hot-selling vehicles such as the Ford Fusion midsize sedan, Focus C-car and Escape cross/utility vehicle.

Fusion inventories will be bolstered once production of the model ramps up this fall at the Flat Rock, MI, plant, Erich Merkle, Ford’s top U.S. sales analyst, says. However, supply of the Focus and Escape likely will remain tight throughout the rest of the summer, as the plants building those vehicles already are running at full capacity.

Focus days’ supply, which now is in the high 30s, should normalize beginning this fall, Merkle predicts.

“Small cars are very seasonal,” he says in a conference call with journalists and analysts to discuss July sales results. “Spring and summer are the peak months, but in the fall and winter, we see small cars drop off a bit in favor of trucks and utilities.”

Focus sales dipped 2.2% in July from year-ago, while Escape deliveries dropped 0.5% and Fusion sales slid 2.1%.

Despite that, overall retail sales were up 19%, Merkle says, marking the company’s best July result since 2005.

Several models performed well, including the F-150 pickup, which posted a 16.8% year-over-year increase to 56,083 units.

Ford is adding a shift at its Kansas City, MO, plant to increase F-150 production, as sales are expected to remain strong despite the launch of new pickups by top competitors such as General Motors.

“In the last three months, Ford dealers delivered over 200,000 pickups, and we don’t anticipate that segment doing anything but slightly increasing as we approach the end of the year,” says Ken Czubay, vice president-U.S. marketing.

The Ford Explorer turned in a strong July, posting a 12.7% increase vs. like-2012 to 14,089. Czubay says Ford is adjusting the mix at its Chicago assembly plant, which also builds the Ford Taurus and Lincoln MKS, to increase Explorer supply.

Ford Edge and Flex CUV deliveries increased 10.2% and 11.3%, respectively, in the month, while the Fiesta B-car turned in a strong performance with an 81.3% gain.

Czubay says much of the Fiesta gain is due to demand in coastal markets, particularly California.

“Fiesta retail sales in Los Angeles were up 71% in July, while San Francisco saw a 79% increase,” he says. “Fiesta retail sales are growing at five times the overall subcompact segment in California.”

Among models with declining sales in July were the Mustang (off 24.8%), Expedition (down 2.4%) and Lincoln MKZ (declining 11.0%).