Zipcar Inc., the Cambridge-based vehicle sharing service that rents cars by the hour, plans to relocate from Cambridge to Boston’s Innovation District next year.

Zipcar has signed a letter of intent to lease space there, but said it is declining to disclose additional details until the contract has been finalized. That’s something that Zipcar expects to happen by the end of the year.

In a statement, Zipcar chief executive Scott Griffith referenced Boston Mayor Thomas M. Menino, who has championed the branding of a section of the South Boston waterfront as the Innovation District.

Advertisement - Continue Reading Below

“I worked with the Mayor and his team years ago to help craft the vision for what has become the Innovation District and we’re excited to join the movement!” Griffith said. “We’re looking forward to the prospect of making Boston’s Innovation District the home of our world headquarters in 2013. The Innovation District will provide Zipcar with exactly the atmosphere we are looking for to attract and retain a great pool of talent as we move closer to achieving our vision of more car sharers than car owners in major cities around the globe.”

The employee headcount at Zipcar’s current headquarters in Cambridge is “over 2oo and growing,” a company spokeswoman said.