A new product to be released in March will turn a car into a rolling Wi-Fi hot spot.

Autonet Mobile, a San Francisco start-up, said Tuesday that it is preparing to release a product for cars that combines 3G cellular access and Wi-Fi technology. With the device, which plugs into a car's cigarette lighter, users will be able to connect to the Internet the same way they do at hot spots or via their home Wi-Fi networks.

The company will show off the system at the Consumer Electronics Show next week in Las Vegas.

"Our thought was to turn the car into a hot spot so people could have the same experience in their car as in their home or office," said Sterling Pratz, Autonet Mobile's CEO. "For the user, it works just like a home router - it's just another Wi-Fi network."

The system's backhaul to the Internet is via 3G EV-DO cellular data access provided by both Verizon Wireless and Sprint Nextel Corp., Pratz said. However, users connect to the in-car Autonet Mobile unit via Wi-Fi, which makes for simple, familiar connections, he said. It also means that users don't need an EV-DO card for their laptop or other mobile devices - only Wi-Fi connectivity that is included in virtually all laptops and, increasingly, in other mobile devices such as smart phones.

Pratz said he expects access on about 95 percent of roads in the U.S., although some of that access will be via older, slower 1xRTT technology, which is still more widespread than EV-DO.

When it can't access faster EV-DO connections, which provide access in the 500 Kbit/s to 1 Mbit/s range, the system will seamlessly fall back to 1xRTT, which has speeds in the 128 Kbit/s range, according to Pratz. He said that his company has agreements with both Sprint and Verizon Wireless and added that the system will select the best available signal.

The device will cost $399, plus a $49 monthly service charge, even for those who already subscribe to Sprint or Verizon Wireless service. The system will likely be available first through rental car agencies. The New York Times reported this week that Avis Inc. will start offering the system in its rental cars for $11 a day starting in March. Pratz said he couldn't yet confirm that, but he said that, in addition to being available in rental cars, the system will be on sale a bit later in the spring.

Pratz, a former race car driver, said the system has been tested at - and well above - normal highway speeds. The system doesn't have trouble when it detects other Wi-Fi networks, Pratz said.

The system has built-in security, including VPN-like encryption between the device itself and Autonet's network operation centre. In addition, the system also will work with corporate VPNs, Pratz said.

Initially, the primary audience will be both families and business travellers who rent cars, Pratz said. But, ultimately, he thinks the system would be attractive to corporate IT because it would enable mobile workers to stay in touch with the home office without needing to stop to find a Wi-Fi hot spot or other type of access.