Want to take the Challenge? Try an online map radius tool, like this one, to show you what's within 40 miles of your city

It's the 40th Earth Day. Most hybrid cars travel 40 miles on electric power. So naturally, the EcoCAR teams – about 200 university students building green cars – It's almost April 22nd and to mark 40 years since the first Earth Day, the EcoCAR teams are looking under their hoods for inspiration… and something that involves the number 40.

As a result, we have the 40 Mile Pledge. For the rest of 2010, every time they hit the road for a day trip, they're keeping it under 40 miles. It's a simple way to conserve energy and drive like you own a hybrid, even if you don't.

Need inspiration? The EcoCAR teams shared a few of their under-40-mile day trips:

• Noxubee Wildlife Refuge's Goose Overlook, a scenic observation platform, is a favorite destination when the Mississippi State team needs a refreshing escape.

• The Georgia Tech EcoCAR team can zip up to Lake Lanier in under 40 miles to go camping, hiking, fishing, or out on a boat ride.

• Some of the Penn State team's favorite under-40 trips include Mount Nittany, which is considered a mandatory hike for any graduate and is only a short ride on the local CATA bus, which runs on natural gas to boot! Fisherman's Paradise is another favorite spot.

• The engineers from Ohio State's team go to the nearby Mohican State Park for outdoor activities, but they also have a few in-town "getaways" like the Easton Towne Center and the Columbus Zoo.

• Meramec Caverns and Meramec Springs – which produces 96,000,000 gallons of water per day! – are a couple of Missouri S&T team's favorite under-40 daytrips.

• For a short getaway, the University of Victoria team heads out to Sombrio Beach for surfing or Sooke Potholes Regional Park for a swim in natural pools carved into the bedrock.            

Want to take the Challenge? Try an online map radius tool, like this one, to show you what's within 40 miles of your city..