Yeah it was an interesting pivot. They started as the electronic version of the "ride board" [like http://resources.mit.edu/resource/apo-ride-board ] and took a while to change.

Here is a press release from Zimride sent circa Thanksgiving 2008 (after they had been underway for about a year):

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STUDENTS TO FIND RIDES HOME FOR THANKSGIVING ON FACEBOOK
Useful Facebook application, Carpool, helps match students for rides home

Finding a ride home for Thanksgiving with friends and classmates has never been easier. Students can conveniently use a Facebook application to share rides home for some home-made turkey. The application built by Zimride is called "Carpool", and having launched in 2007, it has become the most popular online ridesharing service in North America.

Carpool on Facebook is especially popular among students on college campuses, where it has replaced traditional ride boards at student centers with a more convenient online interface. Over 25,000 rides have been posted on Carpool in the last four months. "The growth is unprecedented," comments Logan Green, a co-founder of Carpool. "It shows that not all popular Facebook applications have to involve ninjas and vampires. An application like Carpool helps students find safe rides in addition to cutting their gas expenses and reducing CO2 and it's clear students value that."

The Carpool application uses Google Maps technology to match students traveling in the same direction. After the trip, users are encouraged to leave feedback, to help inform future Carpool users. The application makes ridesharing a more social experience. "It really feels like I'm part of a community," says Corey Earle a student of Cornell University. "I could never trust an anonymous service like Craigslist because I wouldn't know anything about the other users. Using Carpool on Facebook, I can choose to ride with people in my school who I know I can trust.' Carpool on Facebook was built by a team of recent graduates who saw an opportunity to make carpooling more popular at universities across the country. John Zimmer, a co-founder of Carpool, says, 'We're thrilled that university students and administrators are reaching out to us to help make ridesharing become a part of mainstream culture on college campuses." Zimride has worked with over 20 universities since creating the service to build custom systems for their campuses.

If you have a car, offer your carpool today. If you don't have a car, find a ride and get home to the home cooked turkey, stuffing, gravy and cranberry sauce…don't forget to share!

To try out the Carpool on Facebook:
http://apps.facebook.com/carpool

For more information on Zimride visit:
www.zimride.com

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Here was a sample use of a version of the product in a 2011 email:

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Subject: [Reuse-sell] Ride from MIT to NYC or [city] NJ, Depart Oct. 21 1pm, Return Oct. 22 10am

I have rented a car for a trip to [city] NJ.

I am leaving from MIT at 1pm on Fri. Oct. 21.

I am returning from [city] NJ at 10am on Sat. Oct. 22

If you want to share the ride on either of the two directions let me know. I
expect the total rental plus gas to cost me $120. I am looking for someone
to pitch in $20 for each one-way journey.

I have posted on zimride too: http://zimride.mit.edu/ride/share?ride=[id]

Thanks,
[name]

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I think the deal is that the company pivoted mid-2012 to an Uber clone and sold the Zimride subsidiary to Enterprise in 2013.

I wonder how much of the Zimride engineering team went to Lyft during the pivot.

I wonder who has the longest tenure at Enterprise's Zimride subsidiary and how they feel about working there vs. working at Lyft.