Success is the occasion for chest bumps in the end zone but the failure rate is high. Mercedes-Benz gets credit for introducing seat-belt pretensioners in the S-class, but rear parking markers that popped out of the fenders were quickly made obsolete by backup cameras.

BMW was widely criticized for its redo of the 7 series in 2002 that brought the overly complex iDrive accessory controller and the blunt styling of the “Bangle Butt” only to see both features adopted by other manufacturers.

And Mercedes created the modern luxury sedan segment with the first S-class in 1972. BMW followed with the 7-series in 1977 and Audi came along with the A8 in 1984.

The rivalry has become more intense in recent weeks as both Mercedes and Audi have announced goals to sell 1.5 million vehicles worldwide by 2015.

With so much at stake, the introduction of Audi’s 2011 A8 takes on added significance and the automaker isn’t leaving much to chance. The new car bristles with unique gadgetry, some of which prompts the response: “How did they think of that?”

Chief among these is what’s called the “Multi Media Interface with MMI touch.” Mere voice recognition for controls isn’t enough for Audi. On a small pad set next to the gear shift lever, the driver can identify destinations for the navigation system by tracing letters and numbers with his fingernail etch-a-sketch style. Better still, the system can identify a wide spectrum of languages and characters, including Cyrillic, Chinese, Cantonese, Japanese, and Korean, depending on where the car is purchased.

That’s not all. The internet is steadily making its way into the car. The Audi makes it possible for users to route their trips on Google Maps and get real-time route updates through Google Earth. That’s just in case the traditional hard-disc navigation system didn’t inform you that the highway was flooded and the bridge was washed out.

Particularly welcome is the optional radar-based cruise control and lane-departure warning systems. Veer out of your lane and the steering wheel vibrates to get your attention so you can get back on course again. And if the system detected the possibility of a rear end collision, the seatbelts’ tension is tightened, and the headrests are adjusted.

Surprisingly absent on my test car were automatic door closers, one of those optional luxuries that begins to feel like a necessity when you leave one of the heavy doors partially unlatched.

The whiz-bang stuff may thrill some drivers and produce bragging rights, but what is the car like? Audi pioneered the aluminum space frame, which it says weighs 40% less than a comparable steel structure, and the latest generation is 25% stiffer. The ride of the new car is settled and quiet, though one A8 owner told me the car feels heavier than his older one.

Audi also pioneered all-wheel-drive. It is now available on competing marques as well, but they are not as committed as Audi, whose Quattro system is standard equipment.

The A8 is propelled by an improved 4.2 liter engine with 372 horsepower, which is 22 hp more than the previous model, yet it gets 15% better fuel economy. A combination of busy highways and empty country roads yielded me 21 mpg. Zero to 62 mph is estimated at 5.7 seconds, fast enough for any legal purpose.

Though Audi is now the top-selling luxury brand in Europe, its cars still sell at a discount to its higher-profile rivals. The base sticker price on the A8 is $78,050 versus $94,600 for the Mercedes S-class.

Bargains are not usually associated with premium automobiles, but by that measure, the Audi A8 qualifies as one.