You see them most everywhere, ambling along America's highways and byways like gentle whales. Inside sit recently retired couples who have managed to shove the bulk of their earthly possessions into a full-size, bus-size RV. And 40-footers aren't uncommon. They're even towing a Mercury Sable because, let's be honest here, nobody wants to try and park a rig of this size anywhere near an Olive Garden. Bigger is of course better -- so say the great state of Texas and a large portion of what makes up our American consciousness. But if size and nothing else mattered, Alaska would be twice as fabulous as Texas! And as any Lone Star Stater will tell ya, that simply ain't the case.

Meet the Airstream Interstate 3500, a luxurious and compact recreational vehicle. Compact is a relative term, as the Interstate is based on a full-size dually Mercedes-Benz Sprinter van that shows up "naked" weighing 5562 pounds. Once Airstream is done with its converting, the 22-foot-long, 80-inch-wide van tips the big scale to the tune of 8436 pounds, with a GVWR of 11,030 pounds and a GCWR of 15,250.

However, the 3.0-liter Blue Efficiency V-6 engine is more than up to the task of moving around an extra ton, a startling fact when you consider that the small diesel makes just 188 horsepower and 325 pound-feet of torque. Even with those (relatively) small numbers, our Interstate had no trouble whatsoever keeping up with traffic and maintaining a 75-mph cruising speed up and down the 101 from Los Angeles to north of San Francisco.

Better still, loaded up with me, my wife, our dog (a 13-pound miniature pinscher mutt named Knuckles), and enough stuff for a six-day road trip (including 26 gallons of fresh water, 27 gallons of gray water, and 14 gallons of liquid petroleum gas), the Interstate averaged 18.6 mpg over 934 miles. Not bad at all and, as Airstream points out, 30 percent better than a similarly sized and equipped gasoline-powered RV.

Aside from head-scratchingly decent fuel economy, the other surprisingly good attribute of the Interstate is the big boy's maneuverability. From freeways to dirt roads to cramped parking lots and even a racetrack paddock, the Airstream was simple and easy to finesse into place. Forget the Olive Garden, you could effortlessly take the Interstate through a Mickey D's drive-thru if it had 10 feet of clearance (with the A/C unit in place, this rig stands 9 feet, 8 inches tall). This isn't too surprising as the most striking physical feature of the Airstream Interstate is its width, specifically the lack thereof. You won't notice at first glance, but poke your head down around the rear of the vehicle and you'll see that this mini RV is in fact a dually. Only unlike our heavily extroverted American duallys, the wheels fit within the body.

One area where the Interstate didn't impress was inside. Oh, sure, the materials were pretty nice -- glossy, polished gray wood with white leather and lots of shiny chrome accents -- though not nearly as elegant and impressive as the 16-foot Airstream Sport my wife and I spent our wedding night in. Also, all the pieces seemed to be screwed together just fine. So what was lacking? In a word, space. There's just not very much room for your stuff, at least compared with other RVs I've taken on trips. And the Interstate is by no means small.

Now, a caveat, if I may. The wife and I packed our bags for a near-weeklong trip. I don't know about you and yours, but for us that's a bunch of stuff. Moreover, we were headed up to Infineon Raceway so I could reprise my recurring role as a 24 Hours of LeMons Supreme Court Judge (AKA Judge Jonny). Not only that, but LeMons Chief Perp Jay Lamm hired my wife, the much-heralded sideshow performer Amy Amnesia, to freak out some of the more miscreant drivers with the possibility of having to hammer a nail up their nose. Meaning that poor Knuckles rode the 450 miles up to Sonoma County lying on a bed of nails covered by a ratty green towel.

The possibility exists then that we might have brought more stuff (and more oddly shaped stuff) than Airstream anticipated. But I think the truth is somewhere in the middle. The Interstate's interior is half-ringed with head-level storage bins. I had to go pick up the Airstream in the Valley, run home to grab the wife, dog, and stuff and then hit the road, so the aisle was hastily clogged up with luggage. However, if we owned our own, we'd have packed it differently and as a result would have had more space. Enough? Yeah, probably, even with Amy's ladder of machetes on board. But imagine if we had kids? Mercedes-Benz does make an extended-length version of the 170-inch-wheelbase Sprinter (the Interstate is based on the standard-length 170-inch-wheelbase, high-roof Sprinter Van), which might be the ticket in terms of packaging, though at the expense of mileage and motility.

Speaking of packaging, Airstream saw fit to include everything, including a kitchen sink with a vegetable sprayer. Running it all down, you get seating for six, sleeping for four (though really, two) a restroom with a shower, a full kitchen with a microwave, and a 19-inch flat-screen TV. Literally all the comforts of home, and we put these to good use when we parked the Interstate on Infineon's hot pit to use as our mobile LeMons HQ. The 13,500-BTU air-conditioning unit running off the liquefied propane generator had no trouble keeping Knuckles cool (since the bed of nails was in use, she had moved herself to the front seat), while the extendable awning provided excellent and ample shade for the rear seat from a 1975 Citroën DS we use as a couch.

And the Interstate's usefulness didn't stop there. One of the more classic 24 Hours of LeMons penalties is simply called Arc Angel. Long story short, good pal Christine Rotolo dons a pair of white angel wings and welds a representation of a barnyard animal to your race car. Trouble is, welders need electricity. Solution: Plug the welding machine into the Airstream Interstate -- what could possibly go wrong? As it turns out, nothing. The Arc Angel was able to weld about a dozen pigs, rats, roosters, and humping bunnies over the course of two days without blowing a single fuse or having any sort of power interruption issues whatsoever. As Larry David would say, that's pretty, pretty, pretty good for a small RV.

Taken as a whole, the Interstate represents a curious mix of attributes. On the positive side, the Airstream's a good-looking and well-appointed alternative to a big old road hog. It's not as handsome or iconic as an actual Airstream trailer, but then you don't have to mess around with a trailer hitch, either. Speaking of not towing, the Interstate is surprisingly nimble and easy to park, even in medium-dense cities. And nearly 19 mpg for an RV is great news in the modern world of $4-per-gallon gas. Still, $121,274 is not cheap by any definition, especially with slightly used full-size motorhomes on fire sale everywhere for less. Finally, it's just not that spacious. But that might be the entire point.