Imagine a Toyota Prius, but faster, cleaner and greener. Such a car is coming soon and will launch at the Detroit auto show in January 2009.

America has fallen for the Prius in a big way, no doubt about that. Five years on, through an extraordinary combination of style, engineering and marketing, Toyota's fuel sipping hybrid remains the absolute gold standard for eco cars in the industry.

The next generation, however, has all the makings of an even bigger hit. That's because it will be a touch bigger so offering more space. It will come with stronger 1.8-liter hybrid performance yet at the same time boast even better economy and class leading emissions, if early word is correct.

In other words, everything Americans like now about the Prius, including its unique design and crusading eco image, but in a 'smarter,' more high-grade package.

Yes, 2009 marks the point at which the Prius shifts gears and moves up to the next league. The Prius up until now has been just one model but as previously reported in AutoObserver, Toyota plans to spice up the action with a range of different Prius models as it closes in on its bid to be making 1 million hybrids per year by the early 2010s.

While it's still of course firmly under wraps, a well-placed Toyota source says the next generation Prius looks good. "Still Prius-eque, but a bit bigger and more solid looking."

Sources suggest that the next Prius will be some three to four inches longer and about an inch wider, but crucially will not be significantly heavier.

Environmentalists love the smooth, seamless power delivery of the Prius, its ability to run on clean electric power, its strong economy numbers and, not least, the pure, earth-friendly image it gives off.

All that will continue, with two provisos. One, Toyota will re-engineer the Prius' unique gas engine/electric motor/battery powertrain to make it more efficient, more tightly packaged and to extend the driving range using battery the electric motor.

Two, Toyota will install a bigger 1797 cc four cylinder gas engine to cope with the bigger body and counter criticism in some quarters of the weedy performance of the current 1.5.

With the new 1.8, output's expected to shift from today's 75 bhp to a more rousing
100 bhp. This together with a next generation electric motor should lift combined system output from the current 110 bhp to some 160 bhp, sources predict.

As such, the next Prius will be significantly faster, especially off the line and in low to mid range. But advances with the motor, battery and recharging inside Toyota's trick Hybrid Synergy Drive means economy won't be adversely affected.

Quite the reverse, in fact. While the current Prius posts a class-leading 35.5 km/l in Japan's 10.15-mode fuel cycle (equal to 83.5 mpg in the US), Toyota's reported target with the Mk 3 Prius is a stellar 40 km/l (94 mpg) in the same cycle.

Hold the champagne, however. Japan's 10.15 mode is now an old system, far from the modern global standard and especially kind to hybrids in the way it operates (letting them run for an extended period on electric power, which helps deliver wondrous fuel mileage numbers).

Different markets around the world have their own take on exactly how green and frugal the Prius actually is. America, for instance, rates the 2008 Prius at a far more real world-like 48 mpg/45 mpg/46 mpg for city/highway/combined.

Japan's 10.15 mode, nevertheless, while not perfect, does give an idea of the kind of efficiency improvements we can expect with the next Prius (ie some 10 per cent-plus) and suggests, perhaps, that America's Combined rating for the 2010 Prius will lift up to the 50-55 mpg mark.

What about C02? Here and now, the Prius is good for 65g/km under Japan's 10.15-mode banner (but 106g/km in Europe). Nobody outside Toyota knows yet what the Mk 3 Prius will deliver but it will still be one of the cleanest cars on the planet. Indeed, it would be something if the next Prius didn't produce another big statement on CO2.

Toyota meantime is also working on Plug-in versions of the next Prius, of course. The idea06toyotaphev_204 of being able to recharge the Prius' battery pack from a standard domestic socket to extend the vehicle's driving range in electric mode is the next step along way to lifting the Prius into yet another eco stratosphere.

Tests are now under way on European, American and Japanese roads with a fleet of prototypes and Toyota has already announced that it plans to launch sales of Plug In Hybrids (fitted with state-of-the-art lithium-ion batteries) to fleet buyers in the US and elsewhere by 2010.

However, plug-in won't come at launch in 2009 and as widely reported, Toyota has also put back the planned intro of state-of-the-art lithium-ion batteries for the standard Prius due to worries over reliability, pricing, supply and other factors.

Lightweight and high power, Li-Io is the definitely future, however, and Toyota has also said that it is actively now looking into mass production of the batteries in Japan together with Panasonic.

So to start with, the Mk 3 Prius will kick off with nickel-metal hydride batteries, as now. But the battery pack and indeed the whole system will be more efficient and tightly packaged.

Eventually, there will be two body styles, according to a Toyota source. The minivan-style hybrid powered Hybrid X concept from Geneva 2007 could perhaps provide a few clues in that direction.

Toyota is also planning both bigger and smaller Prius-badged models as 'Prius' starts to become an eco brand all of its own. The tiny, two-cylinder, rear-engined 1/X concept from the 2007 Tokyo Show suggests what a future mini Prius could end up looking like.

As for the 'bigger' model, Japan's Nikkei business paper has spoken of an upscale hybrid model with 2.0-3.0-liter engine which could bow as early as 2010, but that yet to be confirmed and may even appear in due course with Lexus badges.

As far as the 2009 Detroit Show intro for the next Prius, we have that from an impeccable source. Toyota president Katsuaki Watanabe himself, no less, has spoken about the NAIAS unveiling, so that surely has to be gospel.

On the production front, numbers for Prius are clearly going nowhere but up, underlining just what a major player the Prius has now become.
. Japan's Nikkei reports that Toyota plans to boost Prius manufacturing by 60 per cent to 450,000 units a year by 2009, elevating it to one of Toyota's biggest brands, alongside Corolla and Camry.

Toyota reportedly built some 280,000 Prius models worldwide in 2007, a jump of almost a third compared to 2006. The Prius is currently built in two plants in Japan and in limited numbers in China, but it's surely only a matter of time before US local production kicks off.

America, after all, has taken the lion's share of Prius sales to date. Toyota's cumulative sales from 1997-2007 bring the hybrid wonder car in at 920,687 units, with the US accounting for 525,543 units. Second, was Japan with 290,805 units.

Amid all the hoopla over the Prius, however, not everyone yet is quite sold. Critics question how economical the car really is in day-to-day driving and continue to debate the worth and all-round effectiveness of the hybrid system, particularly with highway driving. As in, does it all really pay off?

The costs involved in hybrid motoring, including a higher than normal sticker price and outlay needed to replace the battery pack (heaven forbid) have also come under scrutiny. Keen drivers note too that the Prius doesn't ride or handle particularly well and isn't that fast.

But then the Prius is a different kind of car and to date, none of these 'faults' have so far derailed it much in the showrooms or in the hearts and minds of more than half a million American buyers.

If all goes to plan, Toyota will answer these criticisms and more with the coming third generation Prius which is shaping up to be one of the most pivotal cars Japan has ever produced.