The transaction between the two privately held companies, which was announced late Friday by Enterprise, is expected to close in the third or fourth quarter of 2007. Anti-trust regulators in both the U.S. and Canada must approve the deal before it can be completed.

Purchasing Vanguard would help Enterprise expand its airport rental business, the company said. Only 230 of Enterprise’s 6,000-plus branches are located in airports, while virtually all of Vanguard’s outlets are airport-based.

No decision has been made as to what will happen to the Alamo and National brands, said Enterprise spokeswoman Christy Conrad.

Financial terms of the transaction were not disclosed.