Chat 'n Bike in Gaithersburg, Maryland, is a US dealer for Dutch and Chinese four wheelers.The model without electric assist is lighter and more of a road bike.Electric Bike Car Co has several models of their Ebikecar four wheelers that come as pedaled bikes or with electric motors.Both models have electrical assistance as well as pedal power.Alternative Vehicles has a line of four wheelers and trikes mostly made by Pacific Cycles in Asia. Berg Toys of The Netherlands has four wheelers that look like pedaled go-karts, and tricycles as well, including one with an articulated front wheel for body-lean steering called the Balanz Bike.Their 2 Rider model is a surrey-style bike but a little lower than most surreys, with two active pedaling positions and a kids seat adaptor or cargo area up front. They have off-road and street models, and four-seaters for the whole family.There are mud-guards to protect your arms from the rear wheels, and fully-enclosed chains for wet weather riding. Blackbird Designs has a system called the Quadribent that attaches two normal recumbent bikes to make a four wheel, side-by-side "Sociable Tandem" with independent gearing and pedaling. The company can provide doggy platforms and a rumble seat for kids.It has long-travel four wheel suspension, a rear differential with two driven wheels and an upright rider position that is secure on jumps and permits using the legs to muscle the bike.Films (some on the Web site) are impressive when powered by Andy Contes, a former top-ranked pro BMX bike racer.They also do some custom work for special needs riders.Bill Blakie - Very Eco has a quad designed by Bill Blakie of Invercargill, New Zealand.