????RelayRides公司的CEO安德里?海達德鼓勵陌生人借用他的2006版保時捷911——在他自己不用的時候。

????愿意分享——即便是貴重如跑車的物品——是合伙用車的前提。這是一項蓬勃發展的行業，將車主和需要臨時借用汽車的人聯系在了一起。Zipcar從2000年的社區車隊起步，目前規模已經發展到使私人車主可以通過網絡將自己的汽車借給陌生人。其結果是，合伙用車開始動搖長期以來根深蒂固的汽車所有權結構。

????共享經濟在幾年內就得到了迅速發展。人們出租空余的房屋（例如AirBnB的服務）、利用率較低的會議室（例如LiquidSpace的服務），甚至他們的空閑勞動力（例如TaskRabbit的服務）。交通業則經歷了最為巨大的變化。Edmund.com的首席經濟學家萊西?普拉茨在2012年的一項研究中發現，2011年，18-34歲的年輕人購買汽車的數量比2007年減少了30%。如今，合伙用車作為一個領先指標，代表了更廣闊領域的共享服務。

????合伙用車的支持者認為，對車主而言，把車通過RelayRides或者FlightCar這樣的網站租給陌生人可以大幅降低（甚至完全抵消）養車費用。對租車者而言，只在有需求的時候租車比買車更加便宜，在大城市尤其如此。合伙用車和拼車的概念受到了需要用車的年輕智能手機用戶的熱捧。RelayRides的哈達德說：“很久以來，汽車都是自由和成人的象征。但在許多年輕人心中，這一象征顯然已經開始動搖。”

????合伙用車是如何實現的呢？舊金山的FlightCar公司使車主可以在外出旅行時出租他們的汽車。比如，車主們把車停在機場，其他旅客可以在他們回來之前借用。拼車服務公司SideCar和Lyft的總部也設在舊金山，他們把需要用車的人和當地的車主聯系起來，讓車主將他們送到目的地，雙方只需要在應用上進行操作就能實現這項服務。有了智能手機技術的幫助，如今甚至傳統的出租車和豪車租賃服務也在加入這一行列。Flywheel和Uber通過GPS尋找最近的司機，幫助乘客招來出租車或豪華轎車。

????美國城市人口的增長有力推動了這類服務的發展。根據人口普查數據，2010年，美國有超過80%的人口居住在城市，而1980年這一比例只有73%。城市給車主帶來了一系列經濟挑戰，如高油價、保險費、找不到停車位或停車費很貴等。持車成本上升，讓年輕人不再蜂擁前往機動車駕駛管理處。1978年，16歲的年輕人約一半都拿到了駕照，到2008年，這一比例降至31%，2010年進一步降低至28%。對于偶爾用車的人來說，向鄰居租車就足夠了。而對于沒有駕照的人而言，搭車也變得更加容易。SideCar的CEO蘇尼爾?保羅說：“我們的經濟已經從面向產品轉變為面向服務。我們將會把出行從一項產品（購買汽車）變為一項服務（下載這個應用）。”

????When RelayRides CEO Andre Haddad isn't using his 2006 Porsche 911, he encourages strangers to drive it.

????This willingness to share -- even something as valuable as a sports car -- is the premise behind carsharing, a growing industry that connects car owners with renters seeking out a temporary set of wheels. What started with Zipcar's community car fleets in 2000 has expanded to include individual owners making their cars available to strangers over the internet. Carsharing, as a result, is threatening the long-entrenched structure of auto ownership.

????The so-called sharing economy -- people rent out spare bedrooms (AirBnB), under-utilized conference rooms (LiquidSpace), and even their free labor (TaskRabbit) -- has grown substantially in just a few years. But the transportation industry has seen the greatest change. A 2012 study by Lacey Plache, chief economist at Edmunds.com, found that young adults aged 18-34 purchased 30% fewer cars in 2011 than they did in 2007. Now, carsharing may be a leading indicator for a much broader set of services.

????Carsharing proponents argue that, for those who own vehicles, renting them out to strangers through services like RelayRides or FlightCar can defray car payments considerably (sometimes altogether). For renters, paying for a car only when it is actually needed can be much less expensive ownership, particularly in big cities. Carsharing -- along with a revamped take on carpooling, dubbed ridesharing -- has gotten a jolt from smartphone-wielding millennials in need of a ride. "For a long time the [car] was the symbol of freedom, the symbol of adulthood," says Haddad of RelayRides. "That's apparently been shaken up in a lot of younger people's minds."

????How's it work? San Francisco-based FlightCar allows car owners to rent out their wheels while traveling. Users park at the airport, for instance, and let another traveler use their cars until they return. Ridesharing services like SideCar and Lyft, both headquartered in San Francisco, connect ride-seekers with local drivers who use their own cars to taxi people around; they require only an app to operate. Thanks to smartphone technology, even traditional taxi and limo services are working to get in on the action. Flywheel and Uber help passengers hail taxis or limo-type rides using GPS to find the closest possible driver.

????Such services have been largely fueled by a growing number of American urbanites. In 2010, more than 80% of the U.S. population lived in urban areas compared to only 73% in 1980, according to census data. Cities provide car owners with financial challenges like higher gas prices, insurance, and difficult to find or expensive parking. These higher ownership costs have kept teenagers from rushing to the DMV. Roughly half of all 16-year-olds had their driver's license in 1978. By 2008, that figure fell to 31%; in 2010, it was down to 28%. For people who need cars only sparingly, renting from a neighbor is sufficient. For those without a license, bumming a ride has become easier. "We are moving from a product-oriented economy to a services-oriented economy," says Sunil Paul, CEO of SideCar. "We are going to turn transportation from a product (buy a car), to a service (download this app)."