I can't decide what I want from my next long-term commitment. So, as many others do, I'm turning to online services for guidance.

Top Cars, By Age Group

See which car models are most popular in different age groups.

I'm not looking for a date. I need a new car.

Or maybe I really need a truck or an SUV. I don't know, and that's the problem. With more than 1,000 different models available, choosing can be difficult. Buying a car isn't as profound as committing to a spouse, but it is a decision that involves a delicate balance of pragmatic needs and emotional desires.

Taking a cue from romantic matchmaking services, several leading auto-shopping and advice websites, including Edmunds.com and KBB.com, are experimenting with online tools designed to help car shoppers choose a new car. Some of the most popular vehicles sold in the U.S. are the Ford F-series pickup, Toyota Camry and Honda Accord. But for people whose needs aren't met by any of those, the new online tools might be worth a try.

AJ Teixeira, a 43-year-old information-technology professional at the World Bank in Washington, D.C., says that with two kids "what I need is a minivan." But Mr. Teixeira decided instead to hunt for what he likes to drive: cars that are small and sporty.

Joe White on Lunch Break discusses the difficulty of choosing a new car from among hundreds, some would say over 1,000, different models out there.

He tried out Edmunds.com's My Car Match tool, which the online shopping-and-information company says is still in beta test mode. The tool starts with a few basic questions: How many people do you need to fit in the car, how much cargo does it need to carry (a little, a medium load, a large load). It then suggests which of eight types of vehicles you might want.

Mr. Teixeira says he included in his search "convertibles."

From there My Car Match asks users to choose one of three generic cars, even if those cars aren't appealing. The vehicles shown aren't identified by name, though some have photos that indicate what brand they could be. The generic cars are described with subjective attributes, such as "sporty," and some specific criteria, such as miles per gallon.

The result: One of the top choices My Car Match suggested for Mr. Teixeira was a Mazda Miata, a car he already owns. "I thought, wow, what a clever tool. It kind of read my mind," he says.

Some people are harder to match. Sharon Froom, 53, an accountant in Laurel, Md., says she's shopping for a car small enough to tow behind a recreational vehicle, but roomy enough for her husband who is 6'2" tall.

My Car Match suggested small SUVs, such as the Kia Sedona, that weren't on her radar, she says. But she's not certain the system fully captured what she wants. "The questions were too general," she says.

Edmunds.com Chief Executive Jeremy Anwyl says the company worked with academics who have researched how people make choices, in developing the My Car Match tool. "The idea is to understand how people make trade-offs," Mr. Anwyl says. Shoppers will say that good fuel economy is a top requirement, but in reality they will sacrifice miles per gallon to get a car that can comfortably hold five people and a lot of bags.

Most Desirables

Who bought some of America's top sellers in 2011

Toyota Camry

The Toyota Camry is a top-selling car among Americans over 65 years old and younger people with lower incomes. But all age groups rank it in the top five. David Dewhurst

Ford F-150

The Ford f-150 is overall most popular vehicle. Younger people buy it when their incomes top $75,000, while older people of any income rank it No. 1 Ford Motor Company

Honda Civic

The Honda civic is a popular choice for people up to 34 years old of all income brackets. But sales of the Civic fall off quickly as people get older Honda

Honda Odyssey

The Honda Odyssey is not even in the top 10 for most age groups. But 35- to 44-year-olds rank it high when their incomes exceed $100,000. Honda

It's not difficult to see how shoppers might be stymied by the amount of information available on various vehicles' features and pricing. "We collect and produce an absolute mountain of data," says Jeff Bartlett of Consumer Reports magazine. "It can be a bit overwhelming for people to dig through it."

That's why Consumer Reports has been testing a New Car Selector feature for its website that aims to help shoppers create a personal top-10 list by pulling together information from the magazine's road tests, quality surveys and other information. "We're still tweaking it," Mr. Bartlett says.

I took several of the new online tools for a spin to see if they could help resolve the quandary I'm in. During a recent tour of duty in Washington, D.C., I sold my Subaru WRX and commuted by foot and mass transit. Now, having returned to Detroit, I am driving around in a beat-up Chevrolet HHR normally assigned to one of my kids.

The Perfect Car Finder from KBB.com, publisher of the Kelley Blue Book, is a straightforward utility that asks you to set a price range, choose a category of car (sedan, coupe, SUV, crossover, luxury, wagon or electric car) and assign values to several other criteria such as miles per gallon.

In my case, the proposed vehicles that came up were a lineup of medium-size sedans, including the Buick Regal, Ford Fusion, Volkswagen Passat and Infiniti G sedan.

Shopautoweek.com offers users access to the reviews and opinions of the editors of Autoweek, a venerable enthusiast publication. I liked the way the service groups cars—family, green, sporty, hauling, luxury, best value and road trip. But I wasn't sold on the recommendation that the Ford Explorer was my best "road trip" choice. And what if you want a vehicle that can haul stuff and is also sporty?

The Edmunds.com My Car Match tool was by far the most engaging and open-ended. Through a series of indirect questions, the site aims to deduce your true preferences. It took me through five sets of three-car choices, and as I got deeper into the game, I began to worry.

At Round Five, I was asked to choose between two types of cars. One was described as offering "some luxury" but was "not sporty." The other choice was a hatchback that was "minimally sporty" and provided "minimal luxury."

Now, I am kind of a cheapskate when it comes to cars. But it wounded my ego to think that the artificial intelligence behind this application had concluded I was a guy prepared to settle for a minimally sporty car with minimal luxury.

So imagine how much better I felt when the actual result popped up. The perfect car for me, when I placed no limit on price, is the 2012 Audi R8 coupe, a super-high performance exotic sports car that returned a compatibility score of 95%.

Wunderbar! Now all I need is a spare $123,300. When I set a more realistic price limit of $40,000, I was steered to buy the Infiniti G37 sedan. Not a bad choice at all.

Write to Joseph B. White at joseph.white@wsj.com