Every car on CarGurus comes with a verdict: great deal, good deal, fair, high, or overpriced. The site compares each listing against similar cars nearby and tells the shopper where it falls. That one feature brought buyers who did not trust dealer prices, and dealers paid to be in front of them. CarGurus came from a co-founder of TripAdvisor, and it applied the same idea to cars: trust the data and the crowd.

TripAdvisor for the Car Lot

Langley Steinert started CarGurus in 2006, after co-founding TripAdvisor. It began as a place for car fans to swap advice. Steinert then turned it into a search engine for used-car listings, ranked by price and dealer reviews. The money came from dealers, who paid a monthly subscription to list their cars. The bet was that shoppers would come back to the site that told them the truth about price.

Boston's Big Tech IPO of 2017

CarGurus priced 9.4 million shares at $16 on October 11, 2017, above its $13 to $15 range. It opened on Nasdaq as CARG at $29 the next day and closed at $27.58, up 72 percent. It was Boston's first tech IPO of the year. The company later added financing and a business that buys cars directly from owners. CarGurus remains public on Nasdaq under CARG.

Cover: Seven Sages of the Bamboo Grove - No. 2 (Chikurin shichiken sono ni), from the series "Popular Versions of Sages (Fuzoku kenjin ryaku)", Isoda Koryusai. Art Institute of Chicago, public domain. Chosen for seven sages (the car gurus).