Google Maps will show you how packed your train is so you can avoid crowds on your commute - CNBC

But it's also testing something even more granular: the option to see which cars on a specific train are the most crowded on New York's Long Island Rail Road and for transit lines in Sydney.

If, for example, you're searching for trains from New York Penn Station to Long Island on the Long Island Rail Road, you'll see data on how crowded a train is and which cars have the most seats available.

If it's on a railroad that doesn't yet offer the more granular data, you'll still see if the train is crowded or not.

In case your workplace is flexible on commute times, Google said that, nationally, you're more likely to get a seat if you travel at 9 a.m.

Google said the data is provided by the Long Island Rail Road in New York and Transport for New South Wales in Sydney.