NEW YORK (CNN/Money) - Remember when cars had names? Evocative, sometimes powerful, sometimes way off the mark, like Mustang, New Yorker, Bonneville and Capri. They meant something, or at least were easy to remember.

Good old fashioned names are still with us, of course, and new ones -- like Cobalt and Freestyle -- are still being introduced. But many luxury car companies have given up on naming their babies altogether, preferring alpha-numeric nomenclature systems that take the guesswork and focus groups out of deciding what to call a new model.

"It's only the luxury brands that have the luxury of using alphanumerics," said Jim Singer, president of NameBase, a marketing company that has helped create names for some Kia, Suzuki and Renault cars. The implication: a flashy car can sell itself.

Acura, starting in 1995, went from using names like Integra and Vigor for its cars to using combinations of two and three consonants like RL and TSX.

"We would rather have more emphasis on the Acura brand," said Chris Naughton, a company spokesman.

Singer is no fan of alphanumerics for car names.

"You're missing a huge opportunity to communicate more about the vehicle," he said.

Is it fast? Is it rugged? Is it big and comfy? Who knows?

Still, while those serial-number car names may look like someone threw a spoonful of chrome-plated alphabet soup at a car's deck-lid, they really do have meaning. Yes, 530i really does have a story to tell.

These are general rules, by the way, and there are some exceptions.

BMW's numbering system is fairly simple. Numbers, usually odd numbers, indicate the relative size and expense of cars. Everyone has heard of BMW's 3-series, 5-series and 7 series cars. In Europe, BMW sells the bargain-priced 1-series.

The next two digits indicate engine size. The BMW 325i has a 2.5 liter engine. The BMW 330i has a 3.0 liter engine.

The letter i is a holdover from times when fuel injection was something to brag about rather than something you would find in even run-of-the-mill economy cars. In Europe, where BMW sells diesel-powered cars, one can also see the 325d on the road.

Sometimes two letters appear after the number, as in the 325Ci and 325Xi. The first letter indicates a special type, as with the two-door 325Ci coupe or the all-wheel drive 325Xi.

Let's take, for example, the Lexus LS 430. The second letter in any Lexus car's name indicates the body style. An S is a sedan, an X is a sport/utility vehicle and a C is a convertible. The 3-digit number is based on the engine size in liters. So the LS 430 has a 4.3 liter engine, and a GS 300 has a 3.0 liter engine.

The first letter in a Lexus name indicates the relative size and cost of the car. The higher in the alphabet the letter is, the higher the price. For some reason -- a Toyota spokesman wasn't sure why -- the R SUVs are an exception to this particular rule. They are actually the least expensive Lexus SUVs.

Every car Saab makes has a name that starts with the number 9. The 9 simply means "this is not a military vehicle."

Saab 9-5

When the company was founded in the 1930s, Saab was an acronym for Swedish Aircraft, Ab (the Swedish equivalent of Inc.) After World War II, while Saab was still strictly an airplane company, it was decided that all civilian projects should be given numbers starting with 9. The Saab 90 and 91 were civilian aircraft.

Saab's next project was a car. Since it was not a military vehicle, the car was given the number 92. Since the numbers always had to start with 9 it didn't take too long before Saab was into three-digit, then four-digit, car names.

In 1998 came the car that would have been the Saab 90,000. At that point, Saab went back to double digits, but the numbers were now separated. In ordinary text, the numbers are written with a hyphen in between, like this: 9-5. On the back of a Saab, the second digit is offset in a slightly different typeface.

As with BMWs, the second number indicates the relative size and price of the vehicle. If it's followed by an X, as with the 9-2X, that means it has all-wheel drive.

Acura's two- and three-letter combinations mean absolutely nothing. They're just completely made-up combinations of letters.

One exception that rule -- or lack of one -- predates Acura's overall move to letters. When the Acura NSX sports car was in development in the 1980s that name stood for New Sports Experimental.

Cadillac has dispensed with names like Seville and Deville, replacing them with three-letter combinations like STS and DTS. For those with fond memories of those old names, the first letter remains. The STS is the modern descendant of the old Cadillac Seville and the DTS is the rough equivalent of the Deville.

Cadillac XLR

The C in CTS, Cadillac's entry-level model, has no particular meaning. (It's Cadillac's naming scheme and they get to decide what things stand for, so it doesn't stand for Catera, either.) The letters TS stand for "touring sedan." For the performance version of the CTS, the company added a V to create the CTS-V.

The XLR, a two-seat convertible, is the "luxury roadster" of the X series.

Otherwise, an X on a Cadillac stands for "crossover." The RX in the name of Cadillac's SRX SUV stands for "reconfigurable crossover."

Cadillac is in the process of doing away with the Escalade name on its SUVs but hasn't quite gone all the way yet. For now, each Escalade model has a 3-letter addendum on its name: EXV for the crossover version and ESV for the performance version.

The letters in front of Mercedes car names, like E320, indicate the "class." Sedans are C, for the least expensive, E or S, for the most expensive. SUVs are M or the more exclusive G. Convertibles are, in order of expense, the SLK, CLK and SL.

Mercedes SL500

Like BMW, Mercedes scrapes the bottom of the alphabetical barrel in its home continent selling the A-class which is not available here.

The three numbers indicate engine size. An E320 has a 3.2 liter engine, for example.