THE original was billed as arriving just in time for the 21st Century.

Now the new fourth generation Toyota Prius is being heralded as 'the rebirth of the pioneer'.

Pioneer, because the quirky looking hatchback was the world's first mass-produced hybrid-powered car and remains the best-seller in that sphere.

Toyota is claiming new benchmarks in fuel economy, emissions and efficiency from the latest Prius, which is cleaner than ever before with CO2 falling to a new low of 70g/km - almost half the 120g/km produced by the original.

But it's not just about green credentials as the car is driven by a new generation of Toyota's full hybrid powertrain, resulting in the potential for an average fuel return of 94.1mpg.

And the Business Edition Plus variant couldn't be more aptly named as it is extremely tax effective courtesy of an 11 per cent benefit-in-kind rating.

It's also free of the London congestion charge and boasts a 100 per cent capital write-down allowance.

If you don't know how things work, the Prius is capable of operating in petrol and electric modes alone as well as in a combination of both.

Called Hybrid Synergy Drive, the system comprises a 1.8-litre petrol engine, a powerful electric motor, a generator and a high performance battery.

From start-up, Prius automatically operates in EV mode, using electric motor power alone - great for parking or in snail's pace commuter traffic.

The petrol engine is supposedly only introduced under firm acceleration, though in reality it doesn't work out like that as anything but the lightest touch on the accelerator triggers the engine.

And while the ECO setting of the three drive modes - EV, ECO and Power - allows the potential for that fantastic fuel figure, my own overall average was closer to 65mpg.

Having tried the previous model less than 12 months ago, the improvement in driving enjoyment from the new generation Prius is clear - it's smoother, very quiet, handles more positively and feels more spirited.

The car's cockpit-style cabin is also better with its firm, durable cloth seats - comfortable for three across the back - a colour head-up display, seven-inch touchscreen, wireless phone charger and six-speaker sound system.

As for luggage space, there's a deceptively large boot - particularly if a repair kit rather than spare wheel is specified - while you also get front and rear door pockets, an overhead console, glovebox and a console box with a removable inner tray and two cupholders.

During its development the Prius was crash tested more than 400 times to ensure a top safety rating, and systems like a rear cross traffic alert and blind spot monitor are key safety features.