As much as I love riding a two-stroke carbon-spewer around the woods, tearing up the turf and frightening the wildlife, it's not really a very conscientious way to travel. And while electric ATVs are a step in the right direction, just one more step would get you pedal power. That's the idea behind the "Trailcart," a human-powered four-wheeler with permanent four-wheel drive. And while it might not have as much torque as an ATV powered by an engine, it does have one clear advantage: the inventors are trying to keep the weight under 50 kilograms, making it much easier to lift a Trailcart over obstacles that it might not otherwise clear.
The Trailcart isn't on sale yet, so in the meantime you can pick up a nice "Rail Runner" for just $2,000 or so. The Rail Runner is pedal-powered as well, but travels along abandoned railway lines.
Update: Reader "welmoed" writes in the comments:
My husband built a pedal/electric hybrid 4-wheeler last summer. With the current gas prices, it's now our "errand car" -- we use it for one-person errands within a 10 mile radius. It gets a lot of interesting looks! Here's a link to a YouTube video showing the car in action: