Rising fuel prices and the prospects of an economic slowdown had U.S. consumers second-guessing ’07 vehicle purchases, boosting the installation rates of small, low-displacement engines.

Related document: % Engine Installations on ’07-Model U.S. Domestic Cars and Light Trucks

Model-year ’07 marked the third annual increase in the use of 4- and 5-cyl. engines, according to Ward’s annual survey of North American engine installations. They were featured in 31.7% of the 13,452,897 ’07 vehicles built in the U.S., Canada and Mexico, up from 27.7% of the 13,641,012 vehicles turned out the prior model year.

It also was well above the 10-year average of 27.0% and narrowly eclipsed the period peak of 31.6% garnered in model year ‘98.

Not surprisingly, the increase was greater in cars, where 4- and 5-cyl. engines accounted for 58.2% of ’07-model output totaling 5,815,347, up from the prior peak of 53.5% for the 5,866,837 cars assembled in the ’05 model year. The increase in 5-cyl. engine installations, to 5.6% from ’06-model’s 2.5%, is attributed to a move by Volkswagen de Mexico S.A. de C.V., which is equipping its Beetle and Rabbit models with a 2.5L I-5. The I-5 replaces the last of VW’s naturally aspirated 2.0L I-4 engines.

The 5-cyl. powerplant, in its second year of use, accounted for 96.0% of ’07 VW output compared with 43.2% in ’06.

Meanwhile, a new turbocharged 2.0L I-4 accounted for the remaining 4.0%.

The 1.9L 4-cyl. turbodiesel that powered 17.8% of ’06 VW production was withdrawn from the market for ’07 as the auto maker prepared a new line of oil-burners able to meet more demanding diesel-emissions regulation.

In addition, Chrysler LLC’s all-new Dodge Caliber launched in early 2006 as an ’07 model and its extended production run helped raise the bar for 4-cyl. car output.

On the truck side, 4- and 5-cyl. engines powered 11.4% of the ’07 output of 7,637,550 vehicles, compared with 10.2% of the 7,774,175 ’06 models.

The use of 4-cyl. engines jumped 1.9 percentage points thanks to increased output of small cross/utility vehicles, while a dip in production of General Motors Corp.’s Chevrolet Canyon and GMC Colorado pickups, where the 3.7L I-5 is optional, held that powerplant to a 1.5% share of ’07 production, down from 2.2% in ’06.

Light-truck V-8 usage also increased in ’07 to 42.9%, from 41.6% in ’06, as GM and Toyota Motor Sales U.S.A. Inc., launched large pickups with new and more-efficient 8-cyl. engines.

But the car installation rates for V-8s declined to 7.2% from a 10-year peak of 10.2% in ’06, reprising rates of 7.4% and 7.5% for ’05 and ’04, respectively.

Six-cylinder engines took a drubbing all the way around in ’07 due to declining minivan and small SUV output, along with a drop in popularity of V-6-powered small pickups. Only 40.7% of ’07 North American-built light vehicles were powered by 6-cyl. engines, down from 43.8% the prior year, including a decline to 45.3% from 47.6% in light trucks, and 34.6% from 38.8% in cars.

Engines under 3.0L displacement – encompassing most 4- and 5-cyl. units along with some V-6s – edged up to 27.7% for the ’07 production run from 26.0% the prior year, but fell below the 29.5% 10-year average, largely because those engines powered a larger share of vehicles in the mid-1990s.

Those in the 3.0L-3.9L range – mostly V-6s – fell to 33.8% in ’07 from 35.8% in ’06, but still bettered the 10-year average of 31.0%.

Engines with 4.0L to 4.9L displacement, a mix of V-6 and small V-8 engines, edged up slightly to 18.3% in ’07 from 17.9% in ’06, while those of 5.0L or more – mainly gasoline and diesel V-8s, but including some gasoline V-10s as well – held virtually steady at 20.2% in ’07 compared with 20.3% the prior year.

At the same time, E-85 capable engines went into 824,624, or 6.1% of ’07-model domestic light vehicles, down from 7.0% posted in ’06.

Meanwhile, Ward’s found hybrid powertrains accounted for 1.1% of ’07 domestic light-vehicle output; turbodiesels, 2.9%; turbocharged-gasoline engines, 0.7%; and supercharged gasoline engines, 0.2%.

The low rate for hybrids stems from the fact most of the higher-volume hybrid-car models are imported, rather than built in North America.

abinder@wardsauto.com