Interesting WSJ Article on Jag S - Type R... (archive)

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Bragging about horsepower has never gone out of style in the car business, but lately it's enjoying a renaissance. In Detroit, huge billboards tout the enhanced performance of Honda's 2002 Odyssey minivan -- they show the van four times life size and brag of "240 Horsies." Since when are minivans marketed like muscle cars? Since horsepower became a luxury feature.

Back in the days of the original muscle cars, brutish cars with pumped-up engines (and wildly exaggerated power claims) were priced to sell to ordinary Joes. Now, the most extreme muscle cars are mostly souped-up variants of luxury models. Even in middle-market models, power is equated with prestige: Why drive a V-6 Ford Explorer when you can get a V-8?

The competition for the hearts and bank balances of the rich and horsepower-obsessed is increasingly intense. Consider the recent dust-up over the horsepower claims for the Jaguar S Type "R" model, coming to America from Ford's British Jaguar division.

The Jag S Type R landed the coveted cover shot for Car and Driver's May issue, with the headline: "With 400 hp, it's the most powerful Jaguar ever sold in America!" Not only that: At 400 horsepower, the S Type R outranks the BMW M5, an icon among ultra-performance European cars that is rated at 394 horsepower in the American market.

Pulse-pounding stuff. A car company public-relations manager's dream come true. But wait: Even as Jaguar was cranking up the hype for its hot rod, Ward's Automotive Reports, a respected industry newsletter best known for its encyclopedic data on automotive sales and production, challenged Jaguar's 400-horsepower claim. The S Type R achieved that nice round number, Ward's reported, by using a European method for calculating horsepower commonly known as DIN, an acronym for Deutsche Institut fur Normung. (The article is available1 from WardsAuto.com.)

Ward's argued that measured the American way, using formulas codified by the Society of Automotive Engineers (SAE), the S Type R probably boasts 388 horsepower -- more or less.

Jaguar's response: Ward's is correct that the S Type R doesn't rate 400 horsepower under the U.S. method. But Jaguar spokesman Simon Sproule says the company has used the German DIN method to measure the horsepower of its cars for 30 years. Porsche also uses DIN horsepower figures. But BMW doesn't in the U.S. market.

"The 400 number [DIN] is a nice round number," Mr. Sproule says. "It's a number we are using world-wide. And internally the engineers were using DIN. We had a target of 400 horsepower DIN and they got it."

In any case, Mr. Sproule says, Jaguar had no intent to deceive -- and will start reporting and advertising its horsepower ratings using both the SAE and DIN formulas. You can bet Car and Driver will demand no less. The magazine has a policy of converting all horsepower claims to the SAE standard, says Editor-in-Chief Csaba Csere, who faults Jaguar's handling of this case. "We should hold their feet to the fire," he says, noting that the DIN horsepower-calculation method is on its way out even in Europe.

Car and Driver's review of the Jaguar S Type R already applied some heat. The article questioned why the car, priced at about $65,000 compared to between $40,000 and $50,000 for a normal S Type, didn't go as fast as a 400-horsepower vehicle would be expected to. (See full article2)

The Jaguar flap points to a broader problem with the whole horsepower game. Let's set aside how odd it is, more than a century after the dawn of the Automobile Age, that we still compare engine power to the work capacity of a Clydesdale. Horsepower can be expressed in several ways. One horsepower is 33,000 foot pounds of work a minute, which is 745.7 watts by U.S. standards and 735.5 watts according to the German DIN method. In Europe, car makers often report engine power in watts. But in America, watts are for refrigerators and stereos -- we still like to think of our vehicles as trusty steeds. (You can make quick conversions among these measurements using handy Web tools like this one at www.flash.net/~lorint/lorin/convert.htm3.)

Hard-core performance-car enthusiasts now have more sophisticated resources to check car makers' horsepower claims on their own. The advent of relatively cheap dynamometers in the mid-1990s has transformed hundreds of side-street performance garages into unofficial Automotive Baloney Check stations -- a phenomenon studied in a recent paper delivered to the SAE by Rob Smithson and Jeremy Carter of the Southwest Research Institute in San Antonio.

These amateur engine testers already have caused trouble for car makers. In 1999, some buyers of the Ford Mustang Cobra model put their hot rods on dynos and discovered big discrepancies between the car's advertised 320 horsepower and its real performance. Ford acknowledged the problem and recalled the cars.

"There is now a core audience of knowledgeable auto enthusiasts who have chassis dyno results for their cars, but little understanding of the difference between these results, SAE net [horsepower] and actual power delivered to the ground," write Messrs. Smithson and Carter. All of which, the two researchers point out, can be different values. Generally speaking, a real car fighting the wind, the drag of tires and its own weight won't deliver its rated horsepower to the wheels, no matter what.

Car companies have spent a lot of money training consumers to think "more is better" when it comes to horsepower. But as with many other bigger-is-better claims, it isn't necessarily so.

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