OK sure, plopping a mini-home atop a compact car that's all about efficiency might not be the most efficient idea. There will be some, uh, extra drag and weight. No question. But there are some reasons this idea could have some currency.
1: Hook-ups. The prototype at the auto show is based on the third generation Prius. But if the folks who hatched this concept (an outfit called Campinn, according to Carscoop, but the only Campinn I can find is a maker of teardrop trailers) want to make it more feasible, they'll quickly camper-ize the plug-in Prius Hybrid. This way, the value proposition is much more favorable, since drivers could save some serious gas money on a long road trip. RV resorts have been catering to plug-in vehicles for decades, in the form of juice (included in the price of admission) for conventional RV's power systems. Now, RV parks are starting to cater to EV drivers, specifically.
2: Comfort. As a generation of maturing outdoors lovers (i.e., Baby Boomers) age, they'll be increasingly less inclined to sleep on the ground. Many will also be less able to afford monster RVs, thanks to the intersection of higher gas prices and less secure nest eggs (pension? what pension?). A hybrid or fully electric (once EV technology improves) compact campers might be the perfect fit. Plus, the ubiquitous retiree poodle will still fit on the dashboard.
3: Inspiration. This Prius camper might be a bit of a koo-koo krayzay idea, but it could get automotive designers thinking in the right direction. For decades, camper vans provided families a way to take vacations to far-flung parts of the country, seeing national parks and other natural wonders along the way, without breaking the bank. Those days are over. But, with smaller families and an increasingly strong focus on smaller, efficient vehicles, the time is right for more eco-friendly campers.