Talk about “wow factor.”

The 2010 Toyota Prius seemingly will become the first mass-produced vehicle to offer solar panels. Not to power the vehicle. Not yet. But much like many automotive features now deemed “standard” (seat belts and intermittent windshield wipers), this initial application of solar panels could foreshadow a time when an automobile’s power supply is supplemented or eventually supplanted by electricity supplied by photovoltaic cells.

The 2010 Prius’ option on high-end models for a “solar roof” embeds photovoltaic cells into the roof to power a fan that will bring outside air into the vehicle cabin. And, since the Prius uses an electrical air conditioning unit, the solar panels can also power the air conditioning — which can be activated via the key fob within thirty yards of the vehicle to achieve a pre-set temperature.

Pretty slick and wiz-bang to be sure. And the concept is not new. But automotive progress has always been slow. While Volvo offered the first automobile safety belts in 1849, it wasn’t until 1958 that Saab became the first car manufacturer to introduce seat belts as standard equipment in 1958, and it wasn’t until 1964 that most manufacturers offered them on most models.

But even in the face of volatile fuel prices, it will be a while before lower costs and efficiency make solar panels a viable power supply for hybrid or fully electric vehicles. Solar Electrical Vehicles has been adding a convex solar roof to hybrid cars like the Toyota Prius, Highlander Hybrid and the Ford Escape Hybrid. But according to those who know more than I, these solar modules, rated at up to 1200 watt hours per day, only provide enough power (via battery storage) to propel a car in electric mode up to 20 miles per day. If you only drive 20 miles day, great. As for me, I drive 54 miles a day. Add in a cost of up to $6,500 (including installation but not any state or federal credits), and one will have to hope gasoline jumps to more than $5 a gallon to recoup the costs over five or more years. (Other experts indicate that it would be more efficient to use building mounted solar panels that can better collect power by tracking the sun to store electricity for later transfer to the auto. This would also lessen the weight of the car, increasing its efficiency.)

Also, for now, solar panels’ major flaw is that it is incredibly inefficient. Solar panels traditionally convert 6 to 10 percent of the energy in sunrays into usable energy. Recently, top of the line panels pushed this into the mid teens. But nontechnology, allowing for the production of cheaper “solar dots” could push that conversion factor to the 40 to 60 percent range by converting sunlight into electrical energy at the molecular level.

For now, the Prius’ solar roof will be more of a “look at me” feature with an incredible literal and figurative coolness factor.