I see they are imported from China. If I were you I'd check the price on some of the replacement parts and how readily available they are. If you need an alternator or starter for it are you going to be able to get it within a reasonable amount of time? The mileage is good, but I would be most concerned about reliability and replacement parts. Excellent gas mileage wouldn't do you much good if you were having to pay ridiculous prices for replacement parts and it was sitting around waiting on them. I didn't see anything on the web site stating warranty information. Do you know what the warranty period is and what all is covered? I just remember back several years ago when they introduced the Yugo's in this country. From everyone I ever talked to that owned one said it was a piece of crap and it was about as safe as beer can. Then there was the Chevy Vega the engines would usually give up in them at about 50-60K. They might be good little cars/cycles, but I was just throwing out some food for thought. I own a motorcycle, it will get about 37-39 mpg, but parts prices are ridiculous and a set of tires usually last 7-9,000 miles and they are more expensive than some automotive tires. I didn't buy it for fuel economy though I just enjoy riding on a nice day.
My father has one of the older models with the 250cc water-cooled single cylinder engine Truck Model. The speedometer on it is rediculously inaccurate, it says your going 60 when in reality your going around 44 MPH (I've checked this with my TomTom GPS). 44 MPH Seems to be the top speed. The aerodynamics on it are horrible. Extremely cramped too, hardly any room to work the pedals (I'm 5'11" 169lbs.) It likes to vibrate a lot and the brake doesn't seem to be strong enough, you have to jam it to the floor and it still doesn't provide reliable stopping power.
My dad always downshifted to use the engine as a brake for safety reasons. The 250cc models were also rated for 70mpg, but my dad has only gotten 24mpg out of it. Then again, he never drives anything easily. He basically floors it in each gear. I'm sure I could get more out of it but I doubt it'll get 70mpg. Its design is too inefficient.
The 650cc models look much much nicer on the inside (I'll probably post pics of my 250cc model soon) and they should have much more power but I doubt they'll get 70mpg. My 1982 Honda CB650SC Nighthawk, (I just got my permit so I haven't had a chance to mileage test it yet) supposedly gets aroudn 45mpg from what I've seen on internet. Thats reving around 4250RPMs at 55 MPH. I doubt this thing, probably worse aerodynamics than a motorcycle and heavier, will achieve 70mpg. I'd guess in the 40's range in reality. I don't think these things are worth it. Maybe if you bought one, put trailer tires on it (much taller, but only a little wider), put a straight-pipe exhaust, high flow filter, and added a water/meth injection system to make up for the carb possibly running too lean due to small jets then maybe you could get some decent mileage numbers but thats just too much work for a vehicle that is cramped and is almost certain death in a wreck. I think I'd stick with a Geo Metro XFI and just put on some of the upgrades from 3 ech Performance to get about 70MPG. It'd have a lot more power than this thing, more comfortable, parts are easy to come by, fit more people in it, you could actually tow something small if needed.
Summary: Underpowered, seems unstable, cramped, instuments inaccurate, and doesn't achieve anywhere near its MPG claims. Disappointment. Oh, and in Ohio as well as some other states you have to have your motorcycle license for it, 3-Wheels = Motorcycle.