General Motors yesterday announced how much it will cost to convert its cars into a rolling 4G LTE Wi-Fi hotspot. In a nutshell, there will be a three-month free trial period and several paid tiers going up to 5GB of data.

"We're excited to give millions of customers an opportunity to explore the technology without paying extra for a data plan for three months or three gigabytes," said Mary Chan, President of OnStar, the partner company that's providing over-the-air security, navigation, diagnostics, and other capabilities.

After the free trial period, OnStar's subscribers will get 200MB of data per month for $5, 1GB for $15, 3GB for $30, and 5GB for $50.  Non-subscribers can also sign up for 4G LTE but they will have to shell out $10, $20, $30, and $50 for the respective bandwidth amounts.

There's also a 12-month, 10GB plan which will cost $150 for OnStar subscribers and $200 for non-subscribers, as well as a 250MB a day plan at $5 for both OnStar subscribers and non-subscribers.

For existing AT&T customers, a 4G LTE-equipped GM vehicle can be added to a Mobile Share Plan for $10 per month.

Citing AT&T's Data Calculator, the company claims that 200MB is good enough to listen more than 6.5 hours of streaming music, 13 hours of internet surfing, and sending more than 10,000 emails without attachments.

Although GM is not the first company to offer Internet connectivity onboard, they are the first to offer the technology on a broad scale, Chan says. The technology will be first available in the soon-to-be-released 2015 Chevrolet Malibu, followed by Buick, GMC and Cadillac.

GM's in-car Wi-Fi hotspot is capable of supporting up to seven simultaneous devices including laptops, game consoles, smartphones, and tablets.