Zipcar (Nasdaq: ZIP) is looking good in its first quarter as a public company.

The fast-growing car-sharing service saw its revenue climb 34% to $61.6 million. Even if one were to back out last year's acquisition of United Kingdom's Streetcar to get a more axles-to-axles comparison, we're still looking at a healthy 28% spurt.

We're not just talking about growth by rolling into new markets. Zipcar's four established markets -- New York City, Boston, San Francisco, and Washington, D.C. -- saw their revenue climb a combined 25% to $34.4 million, or nearly 56% of revenue.

Adjusted EBITDA clocked in at $2.3 million, a healthy improvement over the $0.3 million it delivered on that front a year earlier. However, the "I" in EBITDA is a dagger, as having to shell out more than $2 million more than it had to last year in debt interest led to Zipcar's net loss widening slightly to $5.6 million -- or $0.17 a share.

Analysts still figured that Zipcar would generate less revenue and post a larger deficit, targeting a loss of $0.23 a share on $59.5 million in revenue.

For now, Zipcar isn't getting in the way of the performance of more conventional auto rental agencies. Hertz (NYSE: HTZ) and Avis Budget (Nasdaq: CAR) have also posted better than expected bottom-line results this week.

Zipcar has given back most of its initial gains since going public at $18 in April, but that could change as investors buy into the asset-sharing phenomenon.

Divvying up underutilized big-ticket assets -- from HomeAway (Nasdaq: AWAY) with second homes to Berkshire Hathaway's (NYSE: BRK-A) (NYSE: BRK-B) NetJets with private jets -- allows participants to live larger than they normally would.

Zipcar isn't just a financially prudent decision. Auto ownership and insurance can be real hassles. There's also the eco-friendly element of having 604,571 members sharing 9,480 cars.

Yes, that's how popular Zipcar is these days. There are 29% more Zipsters than there were a year ago, and they're also driving around more. The average daily revenue per vehicle has gone from $59 to $65 over the past year.

The strong quarterly showing finds Zipcar bumping its guidance higher. It now sees $8 million to $10 million in adjusted EBITDA on $240 million to $244 million in revenue. Analysts were parked at $238 million in annual revenue.

When it comes to growth stocks and story stocks, it's always comforting to stay a few car lengths ahead of Wall Street.

Is car sharing a viable business, or are Zipcar's nearly 605,000 members crazy? Share your thoughts in the comment box below.