Ridesharing cheaper than owning a car?

Owning a car is expensive. What with gas, maintenance, auto insurance premiums and loan payments, drivers spend an average of $8,876 per year on their vehicles, according to AAA.

And in a growing number of cities, ridesharing services like Lyft and Uber provide a new option for drivers who want the convenience of a car without paying for upkeep.

Of course, some city dwellers—like those in New York and San Francisco—ditched their cars long before ridesharing came along. But what if you live in a city like Detroit or Tulsa? When does relying on ridesharing become cheaper than having your own set of wheels?

A recent NerdWallet study compared the costs of ridesharing and car ownership in 50 U.S. cities. It found that, while owning a car is cheaper than ridesharing for the average driver in all the cities surveyed, there are still some drivers for whom Lyft and Uber are good alternatives to car ownership. Consider:

Do you use your car less than average?

Services like Lyft and Uber charge a base rate, which varies from city to city, and charge additional fees based on distance and time. The longer you’re in the car and the farther you travel, the more you’ll pay.

Because of cheaper base rates, some cities are better than others for those hoping to rideshare without sacrificing flexibility.For example, though Cincinnati and Memphis have similar car ownership costs, in Memphis, you can buy 16 rides a week on Lyft and 13 on Uber for the same amount you’d spend ongas, insurance and other expenses. In Cincinnati, your car-owning dollars only buy 11 rides on Lyft and 10 on Uber.

If you can commit to fewer than three car trips per day, you have a better chance of saving money by ridesharing, even if Lyft and Uber rates are high in your city. New York and San Francisco have some of the highest base rates in the country—but excellent public transit.

Can’t use public transit for frequent, longer trips, like your commute? Ridesharing is less likely to save you money. But if you have a short drive to work, or can rideshare alongside other transit options,there’s a good chance you couldlose your car and still save.

Do you have high car ownership costs?

NerdWallet’s car ownership cost estimates were based on a driver with a clean records and a 2014 Toyota Camry, a popular car with low ownership costs. Cars with high rates of depreciation or insurance claims, like the Ford F-250, or low fuel efficiency, like Chevy Camaros, will be less competitive with Uber or Lyft.

If you’ve accumulated a few tickets or claims, insurance may become prohibitively expensive, another factor making ridesharing a tempting alternative. And some cities, like Detroit, also have higher-than-average ownership costs, regardless of your driving record.Detroit’s are almost $4,000 higher than average, the study finds—due primarily to insurance cost.

If you have a gas guzzler or a sky-high car insurance rates, it might make sense to trade your car for ridesharing.

Are you waiting to have kids?

Lyft and Uber can approximate the convenience of having a car, but they can’t replicate it. There’s usually some waiting involved, and if you need to retrieve kids from practices and appointments, your rides—and costs—will almost certainly double.

Ridesharing won’t save money for most drivers who make the average number of daily car trips. And if you use your car more than average?You’re better off keeping it. Childless adults are much more likely to save by trading their car for Lyft or Uber.

Do you have Lyft or Uber?

For some, the costs of Lyft and Uber matter less than a lack of access. There are still many cities in which companies like Lyft and Uber aren’t available, sometimes because of legal battles.And almost 20% of Americans live in rural areas where ridesharing is unlikely to spread—at least anytime soon.

Not everyone can or should trade vehicle ownership for ridesharing. But if you find your car sitting unused in your driveway more days than not, it might be time to let it go and use Lyft or Uber to fill in the gaps.

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NerdWallet is a USA TODAY content partner providing general news, commentary and coverage from around the Web. Its content is produced independently of USA TODAY.