Special Coverage

Chicago Auto Show

CHICAGO – Hyundai has amended its estimated fuel economy for the upgraded direct-injection gasoline 5.0L Tau V-8 that will power both the Genesis and Equus luxury sedans, and the numbers cast the engine in a less impressive light.

Ward’s editors had early access to the 5.0L Tau last fall and tested it in a camouflaged version of the performance-oriented R-Spec Genesis as part of the 10 Best Engines competition.

At the time, the auto maker pegged its fuel economy at 18/26 mpg (13-9 L/100 km) city/highway, based on the U.S. Environmental Protection Agency test cycle.

Editors logged 538 miles (866 km) in the vehicle and ended the evaluation with 18.3 mpg (12.8 L/100 km), according to the trip computer. The engine went on to win a spot on the 2011 Ward’s 10 Best Engines list.

Picking the R-Spec 5.0L was not difficult; its 429 hp trounces V-8s in luxury cars costing significantly more and with poorer fuel economy, based on the initial 18/26 figures.

But this week at the auto show here, Hyundai skins back on its mileage estimate, saying the ’12 R-Spec Genesis with its 8-speed automatic transmission will achieve 16/25 mpg (14.7-9.4 L/100 km), which puts it more in line with rivals.

“Sometimes you have to give up a little bit on optimization of fuel economy,” Michael O’Brien, vice president-product planning and corporate planning for Hyundai Motor America, tells Ward’s on the show floor.

“That’s where the engineers and planners have to sit together and decide, ‘Do we want to get the best number, the best fuel economy, or would we rather achieve a better driving experience?’”

Yet to be released is Hyundai’s fuel-economy rating for the 5.0L in the ’12 Equus, which goes on sale this summer. The Equus is about 400 lbs. (181 kg) heavier than the Genesis sedan, so Hyundai officials say they do not expect the rating for the Equus to be higher than 16/25 mpg. The Equus went on sale in late 2010 with the 4.6L Tau V-8, rated at 16/24 mpg (15.6-9.8 L/100 km).

Hyundai Motor America CEO John Krafcik says he was surprised this week to learn about the lower fuel-economy number for the R-Spec Genesis.

V-8 Fuel Economy: Genesis vs. Field
ENGINE MPG
Audi A6 4.2L TFSI V-8 16/24
BMW 550i 4.4L Twin-Turbo V-8 17/25
Buick Lucerne 4.6L V-8 15/22
Chrysler 300C 5.7L V-8 16/25
Hyundai Genesis 4.6L V-8 17/25
Hyundai Genesis R-Spec 5.0L V-8 16/25
Infiniti M56 5.6L V-8 16/25
Jaguar XF 5.0L V-8 16/23
Lexus GS460 4.6L V-8 17/24
Mercedes E550 5.5L V-8 15/23

“I just saw that number two days ago. We’re looking into the data,” Krafcik tells Ward’s. “I was as surprised as you because we had always talked about this doing better than the outgoing 4.6L Tau.”

The 4.6L Tau, which employs port injection rather than direct injection, earned 10 Best Engines honors in 2009 and 2010 and produces 385 hp and 333 lb.-ft. (451 Nm) of torque.

The engine will remain the volume V-8 in the Genesis (30% of the mix) and is rated at 17/25 mpg (13.8-9.4 L/100 km). Once the 5.0L Spec-R arrives, Hyundai officials anticipate it will account for 5% of Genesis sales. The 3.8L V-6 is expected to be the most popular engine, taking 65% of the volume.

Genesis sales were up 33% in 2010 to 29,122 units, according to Ward’s data.

tmurphy@wardsauto.com