– A couple of times a month, Baltimore resident Patrick Campbell hands the keys to his BMW 335is two-door coupe over to a stranger to drive for a few days.

For Campbell, a 53-year-old marketing consultant who works from home, renting out his BMW and his Audi Q5 sport utility vehicle through car-sharing app Turo has become routine and just makes sense.

“It offsets your car payment if you can rent your car out,” said Campbell, who said he progressed into car rentals after becoming an Airbnb host years ago and renting rooms in his home. “I got very comfortable with the sharing economy and letting people use my stuff, so to speak, but also getting money for it was kind of cool. I can’t drive all my cars at once. Why not share?”

It’s a question more people are asking themselves as mobile apps make it easy, efficient and secure to earn extra income by letting people borrow cars and RVs, stay or eat meals in their homes, or hire themselves out to run errands or help with household chores. Consumers who have become increasingly comfortable seeking out services online have been attracted by competitive prices, flexibility and sometimes, a personal touch.

Businesses that act as online middlemen are increasingly letting people arrange fees to share or borrow goods or services, including companies such as ride share apps Uber and Lyft, accommodation booking service Airbnb, online peer-to-peer credit marketplace Lending Club and Task Rabbit, which matches “taskers” with people who need help assembling, mounting or moving furniture or with handyman jobs.

“We can now use the internet to intermediate,” said Brent Goldfarb, associate professor of strategy and entrepreneurship at the University of Maryland’s Robert H. Smith School of Business. “The internet now allows coordination of these activities in an efficient way.”

Campbell, who also uses an online app to rent out an RV he owns, often gets requests from business travelers from out of state looking to bypass a traditional rental in favor of a nicer car for less money or local people looking for an upgrade for a special occasion.

Turo, a San Francisco-based peer-to-peer network, connects owners who list their cars with renters who register, with the company screening both sides. Owners and renters arrange to meet personally to hand over the keys. Much like Airbnb, car owners write online reviews of renters, while renters write review of owners.

Turo, which expanded nationally in 2012, said total sign-ups — both car listings and rentals — have jumped from 54,000 in the United States and Canada in 2012 to more than 2.3 million last year, which includes 121,000 listed vehicles.

The network credits itself with inventing the type of insurance coverage that makes the arrangements possible. The company offers $1 million in liability insurance through Liberty Mutual that supersedes an owners’ policy during a rental period, covering repair and replacement. The company declined to disclose claims rates, said Steve Webb, Turo’s director of community.