Well, lets think for a minute about why the Metris might not be selling well. I mean the dealer inventory mix is absolutely part of it, and the car dealers lack of knowledge about it is certainly another. But lets look for some other reasons.
The lack of sales of the cargo model is actually more obvious than you might think, and its reason is the new Sprinter Worker model. The Vito, thus Metris, is designed around European city confines. Its designed to be parkable in city garages, and in home garages, because in Europe people like plumbers don't generally have large driveways. Thats why those europeans buy Vitos for not much less than Sprinters. But in the US? Those space issues generally are irrelevant to most US buyers, so they'll spend the extra $4k or so for a much larger Sprinter that gets similar diesel economy to the Metris's gas economy.
And beyond that, while in Europe people do not see a Vito as a luxury vehicle, in the US any vehicle with a Mercedes badge is assumed luxurious and expensive. "You know your plumber charges too much when he shows up in a Mercedes-Benz!" Those of us who have bought one are fully aware that the Metris, over its life cycle cost, is not actually an expensive vehicle. But customers don't, and what customers think is often more important than the truth.
Finally, the dealers are a huge problem. I ordered my Metris through a dealer that I have been using to service my cars for ever and ever, which is why I gave them the sale. I liked almost everybody I dealt with except the main Sprinter sales guy who I ordered the van from. He was a jerk and an idiot. He was in charge of various things- including speccing the dealers lot.
He did not understand that the Metris was not a slightly less expensive Sprinter van aimed at people who just couldn't afford the Sprinter. Thus he specced most of his Metris lot similarly to how he specced Sprinters- stripped. An ordinary plumbers van does not need a lot of things- it doesn't need to be quiet and refined for long drives (you don't take long drives!), it doesn't need Cruise Control, or a trip computer, or comfort seats, or a lot of other things, because what a Plumbers van mostly is, is a mobile warehouse and tool shed that is driven short distances from customer to customer.
The cargo Metris is a different beast. It is smaller, more agile, and less spacious. It is going to be used... for different things. It rides better, and handles better- largely because of its relatively sophisticated semi-trailing arm rear suspension. It is a sophisticated van for people who appreciate sophistication, and are willing to pay for it- at the expense of space. Therefore, most people who order it are going to want extra options- climate control, cruise control, the trip computer, the comfort seats, heated seats, whatever. They are more likely to insist on factory installed partitions and trailer tow packs.
The dealers haven't figure out that point yet, and therefore their lots are full of the types of vans Metris customers don't want. American customers, unlike European customers, do not expect to order their vehicle and wait several months for it. Thats a sales turn off, too.
As for airport shuttle operations, those generally fall into two categories. Luxury, and non luxury. The Luxury ones, 15 years ago, ran Lincoln Town Cars, while the non-luxury ones ran either Ford Crown Victorias or Ford Econolines. The luxury ones, now, run various forms of upgraded Sprinter vans, Cadillac XTSs and Lincoln MKTs. The non luxury ones now run standard-spec Sprinters, almost exclusively.
The non-luxury ones often charge extra for an unfull van, or pick up more than one party on the way. They don't want a 7-8 passenger Metris... they want a 12 passenger Sprinter. A Metris can comfortably seat 5 paying customers, a Sprinter can comfortable seat 10. Double the capacity for an extra 30% outlay. Again, in the American road system, and in most of our cities, the smaller size of the Metris- a major selling point in Europe- is almost entirely irrelevant. Airport Shuttle Company's do not make use of the extra handling capability of the rear suspension, or the extra 18 mph of top speed. And the gas Metris gets similar fuel economy to a diesel 144" Sprinter. Which means double the fuel economy for a full run in the Sprinter.
Finally, families looking for minivans will, mostly, be better served by more mainstream products, like the Chrysler Pacifica. Its plusher, has more of the features families are looking for in minivans, and is more adaptable to how families use them (Ex. seats that fold into the floor at expense of maximum cargo space). I think most people who buy one as a substitute for a loaded Toyota Sienna will be disappointed by its hard plastics and relatively loud cabin, and lack of luxury features such as captains chairs.
It will find its niche. I personally think a luxuriously outfitted (which is not the badly executed garbage Explorer is currently marketing- I saw one!) rear end Metris with a partition would make an excellent low-key limousine, for instance. And the diesel engine that will fix the lack of fuel economy advantage vis a vis the Sprinter can't come soon enough.