When it comes to self-driving cars, the future keeps stepping on the gas. The latest development comes from Google's efforts to accelerate the testing of its autonomous vehicles in California. The Guardian reports that the company has created a "Matrix-like" virtual simulation of part of the state's road and freeway system designed to challenge the cars in various situations. Google, according to the Guardian, hopes California safety officials will use the digital testing rather than road tests to eventually certify the vehicles for use in the real world. The Guardian says it obtained a letter sent by Google to regulators earlier this year suggesting that its digital landscape is at least as rigorous as regular road testing sites. "Computer simulations are actually more valuable, as they allow manufacturers to test their software under far more conditions and stresses than could possibly be achieved on a test track," wrote Ron Medford, Google's safety director for the driverless vehicle program. But state officials, so far, aren't riding along. They've rejected the company's efforts to explicitly allow computerized models in California's testing guidelines, Katelin Jabbari, a Google spokesperson, told reporters. "The driving simulator is a relatively new tool -- we didn't have anything like it a few years ago," she told the Guardian. "It's now a critical part of how we test and refine our software." Google unveiled its latest autonomous vehicle prototype during a huge media event in June. The tiny two-seater has no steering wheel or gas pedal. It does have a "go" button and "panic" stop button, cruises at about 25 mph and is significantly different from prior Google robot cars that had steering wheels and allowed humans to assume control. At the time, Google said it hoped to have 100 of them built by the middle of next year as experimentation continued, though the company says the bubble-shaped vehicle won't be commercially available for some time.