We took our Prius over the mountains a few weeks back. I was looking forward to testing it at the extreme end of its design envelope, with a bulky cargo carrier to boot. This gave me an opportunity to see how much highway mileage would be affected by aerodynamic drag. Yes, yes, I should have stuck to the speed limit, but by not doing so I preemptively squashed a bitching point leveled by hybrid hatas — Prius drivers sticking to the speed limit are always getting in the way.

We nailed 40 mpg on the nose for a 260-mile trip that was 95 percent highway driving. I was pleasantly surprised. Just look at that blob on top of the car. I used the cruise control religiously and pegged the speed 5 mph over the posted limit whenever traffic allowed, which was most of the time.

This cargo carrier probably would not affect city mileage much. Which made me realize that a hybrid designed solely for around-town use could probably nail 60 mpg without giving up space, once you eliminate high-speed design criteria like crash impact and horsepower.

Coming down the hill was interesting as well. Rather than dump energy by heating up brake pads, I gained back a large amount of my potential energy by recharging a badly drained battery.

My wife uses the Prius to do a 60-mile highway commute twice a week. She consistentlty gets in the lower-to-mid 50s on these trips. Based on those numbers, I would say that roughly 20-30 percent of its highway mileage results from its very low drag coefficient. In other words, shape a Prius like a Scion xB and you are going to take a serious mileage hit at highway speeds. Will this place a limit on available shapes of cars that obtain high status via mileage performance? If so, how will manufacturers attract new customers if they can’t show off a new car by the obviousness of its new shape?

David rented a Prius on his recent vacation and wasn’t real impressed with its acceleration. Having driven a Corolla, Tercel, Civic, Pinto, and Cherokee over this same pass gives me a different perspective. The Cherokee, although having 200 horsepower, uses most of that power pushing a heavy box shape through a 65-mph air stream. The Prius has the best acceleration of any car we have owned, other than the 18-mpg Cherokee. I’m sure people accustomed to driving sports cars would find the acceleration of other types of cars pathetic.

However, that does not mean David’s critique isn’t valid. As I already mentioned in the comments field of his post, it wouldn’t cost much and it would greatly increase sales if Toyota would put an acceleration switch on the dashboard of its hoped-for plug-ins that would trade battery range for acceleration whenever the urge strikes. Fly-by-wire technology, which today’s Prius fleet is already using, allows customization of control inputs to suit the user.

I strongly suspect that personal transportation technology is about to take a radical new direction. At first, it won’t be pushed so much by the cost of gasoline as it will be pushed by status seeking, which is why most people today buy a Prius (although the high mileage imparts most of that status). Manufacturers make new models every year to satisfy that itch. There is no other excuse for it. It would make much more sense to just make the same car over and over rather than retool every year. You can’t do that because people want something new and different to one-up perceived competitors. The cars are not really different on the inside. Manufacturers just give them a new look on the outside. Two of the most extreme examples of radically shaped cars (other than the new Priuses), designed as always to grab consumers by their status buttons, are the Scion xB and the born-again VW Bug.

These are ordinary cars on the inside, not much different from the ones made half a century ago. The Scion xB actually gains functionality in the form of interior space, but the Bug is an example of how far designers will go to give up functionality for a different look.