The Yaris uses a 1.5-litre petrol engine based on the second-generation Prius's instead of the 1.8 found in the latest Prius and Auris fuel-sippers. The hybrid system – electric motor, transaxle, inverter and batteries – has been downsized from the larger models to fit into the Yaris without compromising on its spacious interior or 286-litre boot.
The hybrid system offers three different driving modes: Normal, Eco and EV. EV allows the Yaris to run on electric power only for short bursts (something the Jazz Hybrid can't manage). This mode is good while it lasts; the Yaris is silent apart from a slight whirr from the electric motor, but inject anything more than a big toe's worth of pressure on the throttle and the engine kicks back in.
Trying Eco mode once is enough; it saps power too much and makes acceleration either a painfully slow or painfully noisy experience (usually both), as the hybrid system doesn't like to be revved.
So it's best to leave the Yaris Hybrid in Normal mode, which is where its best work is done. Drive at a steady pace and the Yaris Hybrid delivers a decent amount of performance, and it also has a surprisingly good turn of speed off the line. But all this is undermined by the CVT gearbox; you're not likely to be able to enjoy a burst of acceleration as there's a constant drone from the transmission.
And whereas the Prius's hybrid system almost effortlessly and silently blends all the components that go into the hybrid drivetrain (save for the CVT), in the Yaris Hybrid you're continually made audibly aware that under the bonnet is not your average small turbodiesel engine.
The Yaris Hybrid is therefore a car to which you need to adapt your driving style in order to get the best out of it. Gentle throttle inputs are the best way to enjoy driving it, something you'll be rewarded for at the pumps. It's also fun to watch the graphics on the interior screen plotting how efficiently you're driving and whether it's the engine or electric motor/battery pack sending power to the front wheels. And in urban driving conditions you're likely to spend at least 40 per cent of the time driving on electric power only; as usual, it's a case of leaving it in Normal mode and letting the clever electronics decide when to run on all-electric power, rather than sticking it in EV mode yourself.
As for the all-important economy figure, a three-hour test route that took in a decent range of everyday driving conditions returned a figure of 65mpg, versus the official claimed figure of 76.3mpg for the T Spirit we tested (the base T3 and T4 models boast an even more impressive 80.7mpg). It was a highly commendable performance, but it's worth noting that the flat roads around Amsterdam didn't allow for a test replicating the UK's naturally hilly road conditions to be factored into the overall figure.
The Yaris Hybrid rides, handles and steers in much the same way as its conventionally powered siblings, even given its extra weight, 20mm increase in length and the 16in alloys of our T Spirit test car. The mature ride quality is a particular highlight that, coupled with steering that is light but not completely devoid of feel, makes the Yaris Hybrid a fine performer around its natural habitat of town centres.