WASHINGTON (MarketWatch) — America’s growing and continued demand for cars and light trucks produced a 10.1% surge in motor vehicles and parts output in July, according to data released Friday.

The gain helped industrial production more broadly rise a seasonally adjusted 0.4% in July, stronger than economists had anticipated.

The rise in motor vehicles and output could in part reflect decisions by auto companies to keep producing in the summer instead of shutting down to retool. Capacity utilization in the motor vehicles and parts segment surged to 88.6% in July from 80.5% in June.

Even so, there’s no question of strong appetite for cars at the moment. Auto sales may reach their highest level in eight years in 2014, helped by aggressive lending, an aging fleet, and an improving economy. In July, sales were about 9% stronger than last year — admittedly a slower pace than the 22% year-on-year growth in output.

While car sales have boomed this year, the stock-price moves on the Big Three have been mixed in 2014. Chrysler owner Fiat IT:F has climbed 20% and Ford F, -0.68% has gained 13%, but General Motors GM, -1.31% has dropped 17%

Outside of motor vehicles, industrial production rose 0.2%, as a 0.4% gain in manufacturing outside of autos was offset by a big drop in utilities output thanks to milder-than-usual weather.

“Excluding motor vehicles/parts, manufacturing output rose 0.4% in July and gains were widely dispersed across durable goods producing industries, particularly business and industrial machinery, consistent with the trends in core capital goods orders. This, along with solid demand for motor vehicles, will contribute to steady growth in the manufacturing sector, even if not at July’s heady pace, over coming months,” said Richard Moody of Regions Financial in a note to clients.

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