

The Toyota Prius is a car even Stevie Wonder could identify at 50 yards. Its distinctive jellybean shape all but screams, "I care about the environment!," which is one reason there are a million of them on the road. There's an old rule about not messing with success or fixing what ain't broke, and Toyota has taken it to heart with the next-gen Prius we'll see next year at the Detroit auto show.

Spy shots of the 2010 Prius have surfaced over at Next Auto, and they show a car that's a little longer, a little wider and a little more aggressive at the front end. Passengers get more room to stretch their legs and owners get more room for all the groceries from Whole Foods. The 2010 Prius gets fancier headlights and a little more bling inside and out but its profile looks about the same, and for good reason – with a drag coefficient of 0.26, there isn't much Toyota could do to make it any sleeker. There are rumors a Prius wagon and even a convertible, which has been done before and doesn't look half bad, are in the works, but so far they're just rumors.

Speculation aside, the biggest changes to the Prius are under the skin.

Toyota plans to give the super-efficient Prius a little more oomph. Car & Driver says the next-gen Prius will get a 1.6-liter gasoline engine, a slight bump from the 1.5 currently under the hood. That'll make the car a little more powerful but it also will get a few more mpg than the 48 city/45 highway the current model offers.

But *Motor Trend *reports that Toyota's giving the car a 1.8-liter engine producing 100 horsepower. Added with the output of the electric motor, total power rises from 110 hp to 150 between now and 2010, according to MT, but the 2010 will retain the same fuel economy as the current model.

There's some debate about the batteries, with some bloggers and motojournos saying the car will get lithium-ion batteries but others saying Toyota will stick with its tried-and-true nickel metal hydride units. That seems more likely, given Toyota and Matsushita are spending $192 million building another NiMH battery factory. If the Prius gets lithium-ion, look for it to happen after Toyota's put a few hundred thousand miles on the forthcoming Prius plug-in hybrids that will use lithium batteries.

One thing's for sure – the next-gen Prius will be as American as apple pie. It'll be built at a plant Toyota's building in Mississippi to help meet surging demand for a car so hot they're not just holding their value, they're appreciating.

See all the spy shots over at Next Auto.