Rumours that Apple is designing a car have intensified after an automotive test centre admitted that the iPhone maker had inquired about their services.
The GoMentum Station is a 5,000-acre site that features 20 miles of paved roads, including flyovers, tunnels and railway crossings and is built on the site of a former naval base in the San Francisco Bay Area city of Concord.
The facility is operated by the Contra Costa Transportation Authority, which is promoting it as an ideal testing facility for carmakers and tech companies working on automotive technology and describing it as "the largest secure test facility in the world".
According to Jack Hall, programme manager for connected vehicles and autonomous vehicles at GoMentum Station, Apple has "shown interest" in the facility but has not reached any agreement for testing there.
"They haven't said what they want to test. It could be an iPhone," he joked, adding that company representatives have not yet visited. An Apple spokesman declined to comment.
GoMentum Station already has an agreement with Honda, which plans to test automated vehicle systems there, and Hall said his agency hoped to partner with other companies for testing self-driving cars and connected vehicles.
"It's got all the infrastructure of a city," Mr Hall said. "There are buildings, streets and intersections, but no people."
Apple's interest in the centre was first revealed by the Guardian newspaper, which cited email correspondence obtained under a public-records request, and also quoted another official at the transportation authority who said a non-disclosure agreement with Apple barred him from saying any more.
Rumours that Apple was working on a car design first surfaced in February when The Wall Street Journal cited unnamed sources who said Apple is working on designs for an electric vehicle to be sold under the Apple brand.
In recent months, news of a lawsuit from a Massachusetts start-up working on electric car batteries that accused Apple of poaching some of its engineers, fuelled speculation. The action has since been settled.
Analysts are split as to whether the company is likely to be building its own vehicle or simply creating technology that could be used in those made by other firms.