The new program, called "24 Hours of Happiness," will be evaluated after three months and is expected to continue indefinitely, Buick spokesman Nick Richards told Edmunds on Monday.
"This is a way for car shoppers to better engage with the dealership," Richards said in a phone conversation. "We find that when consumers can experience our vehicles, they have a completely different perception of the brand. We expect that this will be the way we do business in the future."
The 24 Hours of Happiness began as a pilot program in May for Buick dealers in the Phoenix, Arizona area.
Richards said more than 50 percent of Buick's approximately 2,000 U.S. dealers have signed up for the new test-drive program. The majority of those dealers are in the brand's largest metropolitan markets.
Car shoppers must leave their car at the dealership in order to take a Buick home. They must also bring their driver's license and proof of insurance.
The cars will be provided from dealers' courtesy transportation fleets.
The list of participating dealers will be available at Buick.com starting on Wednesday.
The 2016 Buick Encore Sport Touring model debuted on Monday, featuring a sportier wheel design and a new turbocharged 1.4-liter four-cylinder engine.
Richards said pricing is not available. The Encore Sport Touring model will arrive at Buick dealerships by the end of the year.
Edmunds says: Buick wants car shoppers to take another look at the brand and hopes this new program will jump-start that effort.