AT&T customers can connect their GM 4G cars to shared data plans for $10 a month

If you were thinking about buying one of General Motors’(s gm) new-fangled 4G cars this summer but were wondering how much that LTE connectivity would cost you, then GM and AT&T(s t) today provided an answer. The bottom line: You can get a link to the internet for as little as $5 to $10 a month, but if you plan to consume any reasonable amount of data on that 4G connection, you’ll have to pony up a lot more.

On Monday GM announced three tiers of data pricing for 30 Chevrolet, Buick, Cadillac and GMC cars debuting this year with LTE radios, starting with the 2015 Chevy Malibu next month. The best option is for current AT&T customers (or drivers willing to become AT&T customers for the sake of their vehicles) on its Mobile Share plans. AT&T is treating GM automobiles much like a tablet: You pay $10 a month for baseline connectivity and then attach the device to a shared data plan.

2015 Chevy Corvette Interior (photo by Kevin Fitchard)

2015 Chevy Corvette Interior (photo by Kevin Fitchard)

I say that it’s the most reasonable because AT&T rewards customers that buy data in bulk. You can buy 10 GBs to 20 GBs per month for between $100 to $150, which you can then divide among all of your or your family’s smartphones, tablets, modems and now cars. So if you’re already relying on AT&T to supply your mobile data needs, adding your new Corvette to your plan isn’t really going to add much cost, and you can get a lot of data to boot.

If you’re not an AT&T subscriber you’ll need to buy your car’s data plan a la carte, and the prices differ depending on whether or not you subscribe to GM’s OnStar emergency assistance or in-vehicle navigation plans. For OnStar subscribers the baseline rate is $5 a month for a mere 200 MBs of data, but the same plan is $10 if you eschew an OnStar package.

GM 4G car data pricing

As you get into the bigger-cap data plans, though, prices level out to about $10 a gigabyte regardless of your OnStar status, which is actually much cheaper than AT&T’s regular smartphone data rates. GM will also sell you prepaid data in two increments: $5 for a 250MB single day pass, and a 10 GB bucket for between $100 and $150 that doesn’t expire for a year.

GM 4G car prepaid data pricing

So how much data will you need to keep your car on the pulse of the internet? It depends on how you plan to use it. When we last checked, GM’s revamped connected infotainment platform didn’t have many apps to speak of, so it’s not like you’re going to use your vehicle the same way you would your iPhone or Android smartphone. But among GM’s app store options are several audio-streaming apps like Pandora(s p), NPR and Slacker Radio. If you plan to use those apps on your daily commute the same way you’d listen to FM radio, then you’ll need much more than a 200MB bucket.

But the real data hog will be the embedded 4G hotspot that will come standard in every GM LTE car. The car will redistribute AT&T’s LTE connection through Wi-Fi in the vehicle, allowing tablets, smartphones, connected game consoles and a variety of other devices to do some real damage to your data plan. If your aim is to keep the kids quiet by streaming cartoons to their tablet from Netflix,(s nflix) then expect to shell out for a monster-sized data package.