Glass roof panels are becoming a popular option in modern cars. Taking the old sunroof and moonroof a step further, you can enjoy all the view you'd get in a convertible with none of the gusts of wind.

The glass roof isn't without its problems though. If you live in a hot and sunny climate you'll already be familiar with the delights of intense heat shining down through a sunroof and cooking you from above. Take that effect and multiply it if the whole roof is clear. Glare can also be a problem.

Research Frontiers has a solution. The company has recently joined with Daimler AG, owners of Mercedes-Benz, to give owners of the new 2012 Mercedes-Benz SLK sports car the option of a glass roof with "smart" glass.

Called SPD-Smart, the glass roof can change from clear to dark at the press of a button. On a miserable cloudy and rainy day you can introduce a bit of brightness and cheer to the cabin with the clear option. On the sort of day that asphalt begins to melt and air conditioning is more important than four wheels on your car, the glass can be made darker to help cool the cabin.

The roof tints using a film manufactured by Hitachi Chemical Co. under licence with Research Frontiers.

Check out a video of the glass in action below: