Once upon a time, it was easy to differentiate between the three German luxury brands. Audi was the lesser-known left-field choice, Mercedes was the long standing, old-school king of the market, and BMW was the up-and-coming player for the up-and-coming buyer. But that was the 1980s. How things change.

BMW and Mercedes each sold more cars than Chrysler in the U.S. in 2014, and Audi is now a real player in the market, with sales up more than 15 percent in 2014 over 2013 (though still at roughly half of Mercedes volume). All three companies sell a wide range of models including an entry-level offering for about $30,000 (base price), various SUV models, and 12-cylinder luxury automobiles approaching or surpassing $150,000. Let's take a look at where each brand sits today.

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Audi

I used to be an Audi nut. Quattro all-wheel drive was a valuable feature for enthusiasts in Michigan. Plus, the cars depreciated hard, so I could afford used examples. Then I had my first drive in a BMW E36 M3, which made me realize Audi's lack of handling dynamics, even on the sportiest versions. Today, most Audi models still aren't my choice dynamically. The R8 (above) is the only Audi that impresses me with its handling. But as BMW loses its edge in the sports sedan world, Audi keeps plugging along with gorgeous interiors. And there's also the low-key image advantage of the four rings versus the roundel and three-pointed star. You don't want a Mercedes or BMW parked in your driveway when the contractor visits to give you an estimate on a remodeling job. For many people, Audi is still viewed as just an upscale Volkswagen.

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BMW

This brand used to be King of the Castle, as far as I'm concerned. That first drive in the E36 M3 (above) led me to own several 3 and 5 Series models. I loved their combination of steering/handling prowess and impressive refinement. Their naturally aspirated inline-sixes sounded great and were smooth, smooth, smooth. I was willing to put up with the yuppie frat boy image because BMW offered a product that drove better than the comparable Audi or Mercedes. Now, I'm not so sure. The F30 3 Series isn't as crisp as the old E90 and the 328i's turbocharged inline-4 lacks the old 3.0-liter six's character. Same story with the 5 Series. Yes, fuel economy is up and emissions are down, but at what cost? BMW simply doesn't stand above and beyond the competition any longer.

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Mercedes

Mercedes always had depth. They didn't blow you away during the test drive, but you grew to appreciate their cars the more you spent time in them. Other than some hiccups with quality (including some rather horrible rust issues) for roughly a decade starting about 1996, Mercedes has stayed quite true to its brand image and heritage. It has a history of building over-engineered automobiles with a sense of quality, above and beyond anything else. I also prefer the driving experience offered in most Mercedes models to most Audi models. Most Mercedes interiors aren't quite as lovely as Audi's, but the latest C-Class proves that cars with a three-pointed star can battle the four-ringed brand inside the cockpit. The CLA-Class (above), however, illustrates how Mercedes has to carefully grow its lineup. The Audi A3 is a nicer car to drive and spend time in. Mercedes' smallest, cheapest car just doesn't feel like a true Mercedes, but the A3 feels like a proper Audi.

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Conclusion

The brands have become more homogenous as they've grown their product lineups, and that's not a good thing. Each had its own set of unique qualities designed to attract individual luxury customers. Audi was all about all-wheel drive. Now BMW and Mercedes offer all-wheel drive on most models, which is a necessity for rear-wheel-drive luxury cars sold in northern states. BMW led in driving dynamics. That's no longer the case. The latest BMWs aren't bad cars, but the brand can't legitimately claim to be "The Ultimate Driving Machine" for each segment it's in. Mercedes once offered a certain level of quality and workmanship not found in the other German luxury automobiles. That gap has substantially narrowed and in some cases, Mercedes has lost its advantage. Though I'd give the BMW 5 Series and the Mercedes E-Class a slight dynamic edge to the Audi A6, this is splitting hairs. They are now very similar, especially to the average buyer. Just run the numbers between all three on their configurators and pick the cheapest, which is a disappointing way to make a choice in the luxury segments.

Each automaker used to build products that made sense to different buyers. Now, each brand is trying to have enough model breadth to please any luxury buyer, and they depend on marketing to differentiate their brands. That may be good for short- and medium-term sales, but what about the long run?