Motor clubs such as AAA used to be a driver’s only option when a car broke down and needed rescue on the road.

With its 49 million members, Automobile Association of America is still a giant in the industry, providing towing, flat-tire changing, lost-key replacement, help with stuck vehicles and delivery of fuel or coolant – as well as travel services and discounts – for an annual fee ranging from about $36 to $100.

But these days, an army of other businesses are offering roadside-assistance plans. Some carmakers, for example, extend free coverage to new cars for the length of the warranty and to certified used vehicles.

Insurance companies can fold roadside assistance or towing benefits into their policies. Oil companies, too, have gotten into the game, as have credit-card issuers. Even cell-phone service providers are supplying on-the-road protection.

While the programs have many similarities – all will give, or reimburse you for, a tow – some have gaps in coverage that can leave you stranded or stuck with an unexpected bill. Plans offered by cell-phone service, for example, typically won’t cover you if you leave your phone at home. And one of our own staffers discovered that his automaker’s roadside-assistance program didn’t cover the cost of towing as a result of flood until his car was dashboard-deep from a torrential downpour.

To figure out whether to go with a plan you get for free, or pay for coverage through a company or auto club, think about who and what the various plans cover. Here are some general guidelines:

l Consider a full-service auto-club plan – such as those offered by AAA, the GM Motor Club, AARP and the Better World Club – if your family has more than one car or if you must cover more than one driver. Check that you are not duplicating coverage you already have from your credit card.

l Go with the automaker’s service that came with your new or certified used car if that’s the only vehicle you own.

l Choose a plan with the most generous towing allowance and trip-interruption benefits if you frequently travel far from home.

l A cell-phone or credit-card plan might be useful, since you can use the coverage in any car.

Auto-club plans typically follow the member, providing coverage no matter what the vehicle, in some cases even for rentals. Some of the plans, moreover, offer extras that could help out in a real pinch. Two versions of the AARP plan, for instance, provide $1,000 toward your legal defense if, say, you received a speeding ticket, and payment of up to $1,000 to any hospital emergency room 100 miles or more from home.