Imagine, for a moment, your life a decade or two into the future. You’ve long since moved from your apartment in the city, and now you’re in a house in the ‘burbs. Your friend on the other side of town calls you up to say corporate marketers are handing out free cookie dough ice cream ‘round the corner and you need to get over there right now. You could take your own car to get across town, but traffic is a nightmare. It would take hours. What if, instead, you took a smaller vehicle nearer to town, got the bus through the center and switched to a similar vehicle at the other side, cutting the journey down to like, 45 minutes?

Assaf Biderman, associate director of MIT’s Senseable City Lab, believes this mode of transport will not only prove to be faster, but also essential for the overall health of cities. Populations are set to swell far beyond current levels in the coming decades, maxing out the limitations of current street systems. Enter autonomous cars, electric propulsion, and ride-sharing along with one- or two-person vehicles for part of their journey.

“Successful solutions will be those that can bring the pleasure back to moving around a city,” Biderman tells Inverse. “It’s a very important part, and the individual experience of a trip, your personal experience of it, is going to be in the heart of it.”

In 2000, Shanghai had 16 million people, twice the size of New York at the the time. In 2014, it had 24 million people, three times the size of New York. Getty Images / Feng Li

By 2050, two-thirds of the world’s population will live in cities, resulting in more people on the sidewalks and the subways, with more cars on the streets. Biderman’s theory would help reduce the amount of space taken up by cars. But with the ice cream scenario, it’s not enough to want to switch from a smaller vehicle to a bus to visit your friend. We need new technologies to make it as convenient.

Self-driving cars are one way to make traveling through these future cities more fun. Beyond the free time not spent clutching a steering wheel, there’s efficiency that results from a four-lane freeway filled with autonomous cars. Research by Princeton University in 2014 showed that by the year 2035, there will be enough self-driving cars on the road to allow them to move closer together at speed, with each car’s sensors acutely aware of other vehicles. This will lead to a 35 percent more efficient use of space.

Ride-sharing is another way we’ll get around cities in the coming decades. An MIT study published in January showed that systems like UberPool could increase efficiency so that a system of four-person cars would lead to a 98 percent efficiency rate, which results in something like a wait time of 2.3 minutes to be picked up.

While big-body sedans will always have a place in the culture as symbols of coolness, power, tradition, and status, their engines seem destined for replacement with electric motors, and autonomous tech to control them won’t be far behind. Cars designed to thrive in a crowded city — sedans or otherwise — will be the ones that win out.

At least, that’s the theory. One of the most common sights on the road today is the five-seater sedan. This makes sense for a family, but not so much for a single person commuting to work, or for a group of people all moving in the same direction. Biderman believes that, because of the rise in capacity demand, we’ll need to take drastic action.

“In order to move people more effectively through a city, we will need a range of vehicles, from autonomous buses and vans, like 15-seater vehicles, all the way to one- and two-person vehicles,” Biderman says. “There’s almost no work going into one- and two-seater vehicles, even though they will probably represent the biggest portion of the solution to urban mobility.”

Was the Corbin Sparrow ahead of its time? Flickr/classiccarshow

Biderman rejects more radical solutions like flying cars. Dubai plans to launch a [flying taxi service](https://www.inverse.com/article/27890-dubai-autonomous-taxi-drones-july) later this year, using the EHang 184, and Uber is even considering a system that combines a vertical-takeoff-and-landing vehicle with traditional cars on either side of the journey.

“The whole idea of flying vehicles in the city, to me doesn’t make much sense,” Biderman says. “There’s a reason why we’re all on the ground, a lot lower energy state.”

In the ice cream scenario, you might use an app to hail a one-seater vehicle to get into the city, switch over to an autonomous bus, then switch back to a one-seater closer to your friend’s house. The buses would serve “trunk routes” running through the busiest parts of a city to make space usage as efficient as possible.

The alternative doesn’t bear thinking about. Imagine driving your personal five-seater car closer and closer to the city, as more people try to use the same roads to get to varying places. You wouldn’t get to the ice cream in time. It doesn’t have to be this way.

“We want to make a small and nimble vehicle, something that’s lightweight, uses renewable energy, has many other advantages than increasing the amount of people you can put through the road,” Biderman says.

Worth noting, although it’s covered elsewhere at length, is the fact that electric motors don’t release the sort of carbon into the atmosphere that gasoline-powered engines do.

This solution could complement other forms of transport, like families using a sedan to all visit a relative, or a minivan transporting a team from a little league baseball game. But visiting your friend alone? There has to be a better way.