What would it take for you to give up your car? An all-access pass to a bicycle, maybe, plus some safe lanes to ride in? A smartphone, stocked with apps for cheap ride-hail services? A competent public transit system? A chauffeur, willing to drive you around instead? Lyft, the transportation service provider that has always said its goal is to get more Americans out of their personal cars, would like to find out.

On Wednesday, Lyft announced that it would expand its “Ditch Your Car Challenge,” an attempt to both promote its services—the company makes the whole idea of not owning a car a little easier, goes the argument—and to continue to cast itself as a traffic-busting, city-friendly transportation option.

That reputation has taken a bit of a hit lately. A report published by former New York City transportation official Bruce Schaller this summer suggests that Uber and Lyft have added 5.7 billion miles driven across nine US cities in the past six years. People might not be ditching their cars after all, but simply generating more miles and more emissions, as drivers circle to find passengers and clog up lanes, bus stops, and cycling paths with their pickups and drop-offs.

Which is partly why Lyft is going multimodal. The challenge (OK, technically more like a sweepstakes) works like this: Roughly 2,000 participants from 35 cities (including Miami, New York, Pittsburgh, and Salt Lake City, along with Charlotte, North Carolina, and Nashville, Tennessee) will apply to be randomly chosen to pledge to ditch their cars for a month. In exchange for their fidelity, they’ll receive $300 in Lyft Shared credits, a one-month Zipcar car-share membership and $100 drive credit, $105 in public transit fares, and $45 to go toward a bike-share option. (These figures might vary slightly by market.) The catch: Participants have to actually own a car to ditch.

“In order to get someone out of their vehicle and saving money, using more sustainable modes, they need to have a range of options—it’s not just about one,” says John Zimmer, Lyft’s president and cofounder. So it makes sense that Lyft recently has made a number of big moves in the not-a-car space. In addition to its rebranded and reconfigured shared ride option (now Lyft Shared instead of Lyft Line), the ride hailer now owns Motivate, the largest bike-share network in the US. It’s gotten into scooting too, launching pink-striped service in Denver and Santa Monica, California, with the pledge of more scooters on the way. Plus, the company announced over the summer that it will offer public transit integration, allowing users to plan train or bus trips from within the app.

There’s reason to believe that Zimmer’s strategy will work—for some people. Research has suggested that car-share alone can help a few urban dwellers make the big decision to reduce or eliminate their permanent wheels. A 2016 study by UC Berkeley researchers, sponsored by the US Transportation Department and the company Car2Go, found that 2 percent to 5 percent of active members in five North American cities had sold their vehicles because of the ride-share option. Some older work by some of that same research team suggested that car-sharing is particularly good at convincing users to nix their older, less-efficient vehicles, the sort that clog up the air.

But transportation research also suggests that challenges like Lyft’s might not touch upon the most interesting, and unfortunately, harder to measure population: Those who choose not to buy cars at all because there are better options available. In that 2016 Car2Go study, between 7 percent to 10 percent of users reported they hadn’t bought a vehicle because alternatives were available. It’s not ditch your car—it’s choose not to have a car to ditch in the first place.