The CityCar electric automobile, developed and prototyped by Smart Cities, is designed to meet the demand for enclosed personal mobility – with weather protection, climate control and comfort, secure storage, and crash protection – in the cleanest and most economical way possible. It weighs less than a thousand pounds, parks in much less space than a Smart Car, and is expected to get the equivalent of 150 to 200 miles per gallon of gasoline. Since it is battery-electric, it produces no tailpipe emissions.
The architecture of the CityCar is radical. It does not have a central engine and traditional power train, but is powered by four in-wheel electric motors. Each wheel unit contains drive motor (which also enables regenerative braking), steering, and suspension, and is independently digitally controlled. This enables maneuvers like spinning on its own axis (an O-turn instead of a U-turn), moving sideways into parallel parking spaces, and lane changes while facing straight ahead.
Shifting drive to the corners in this way enables the CityCar to fold to minimize parking footprint, and to provide front ingress and egress (since there is no engine in the way). This dramatically changes its relationship to streets and cities. It can park nose-in to the curb in far less than the width of a traditional parking bay, and it can park at very high densities. It is possible to park three or four CityCars in the length of a traditional parking bay.
The front compartment of a CityCar accommodates passengers and the rear compartment provides generous storage for baggage, groceries, and so on. When a CityCar folds, the baggage compartment remains level and low for easy access.
CityCars accommodate two passengers, which suits them to meeting the requirements of the vast majority of urban trips without excess capacity. They are designed for intra-urban trips, which are fairly short between recharge opportunities. This fits them gracefully to the capabilities of battery technologies that are presently available or likely to be available in the near future. They are not designed for inter-city travel, for which different technologies are more appropriate.
Overall, CityCars are smaller and simpler than traditional automobiles, and in principle much more economical to manufacture. Most of the mechanical complexity is encapsulated in the wheel units. These can be designed to have a standard interface to the chassis, and their cost can be driven down through competition and innovation – much as with disk drives for personal computers.
Lithium-ion batteries are housed in the floor of the CityCar, which provides a large amount of space, keeps the center of mass low, and facilitates cooling. Recharging can be accomplished with inexpensive home charging units, and with units installed at workplace parking structures. More interestingly, it seems feasible to provide automatic recharging in parking spaces, much like the recharging of electric toothbrushes in their holders. This extends the principle of rack recharging as employed with the GreenWheel and theRoboScooter.
Two-seat CityCars do not, of course, meet the requirements of urban trips. But we assume that a diverse, carefully balanced urban vehicle fleet will also contain a component of four-seaters and larger vehicles. By providing two-seat CityCars, particularly in mobility-on-demand systems, we can take care of a large proportion of the demand with great efficiency.
William J. Mitchell, MIT Professor of Architecture and Media Arts and Sciences
Ryan Chin, PhD Candidate, Smart Cities, Media Lab
Chih-Chao Chuang, Smart Cities, MS Candidate
Wayne Higgins, MArch, Dept. of Architecture
Will Lark Jr., PhD Candidate, Smart Cities, Media Lab
Raul-David "Retro" Poblano, MS Candidate, Smart Cities, Media Lab
Peter Schmitt, PhD Candidate, Smart Cities, Media Lab
Andres Sevtsuk, PhD Candidate, Dept. of Urban Studies & Planning
Mitchell Joachim, PhD, Dept. of Architecture
Axel Killian, PhD, Dept. of Architecture
Philip Liang, MS, MIT Media Lab
Franco Vairani, PhD, Dept. of Architecture
Patrik Künzler, MD, University of Zürich
Collaborators from GM
Future Car: ABC Television Australia. 3/25/2010
"Transport," Big Ideas for a Small Planet, Sundance Channel, May 27, 2008
"Future of Architecture," BBC Television Documentary featuring the CityCar, June 2006.