Toyota Prius review: closer than ever to guilt-free motoring

Facts and figures: they may be tedious yet impressive conversational dead ends, but they are precisely what defines this latest Toyota Prius and will delight your inner nerd. The two key numbers are 72.4mpg and just 89g/km of CO2. In range-topping T Spirit form, its larger 17-inch wheels change those figures to 70.6mpg and 92g/km. Better still, the lower figures remain entirely unchanged during the urban cycle, courtesy of the electric hybrid system.

Toyota Prius hybrid system and efficiency

This entirely new Prius represents evolution rather than revolution. Anyone anticipating a leap on the scale of the change between the first and second generations may be underwhelmed. Nearly everything has improved, but it achieves those marketing-friendly numbers using broadly the same technology. The familiar formula remains: a petrol engine, an electric motor and a battery. It has been given an eco-focused polish, however, with options including remotely activated air conditioning, allowing the cabin to be cooled via the key fob three minutes before you climb in. Roof-mounted solar panels can also keep the ventilation running when the car is parked.

That evolution should not be mistaken for Toyota-speak for superficial alterations. Every component with scope for improvement has been addressed. Battery voltage rises from 500V to 650V; higher voltage means fewer amps and therefore reduced heat losses in the cables. The battery itself is smaller, 90 per cent of the hybrid system is new, and the exhaust even features a valve that directs heat more efficiently into the engine coolant, helping the whole system reach its ideal operating temperature more quickly.

More power, but mixed real-world economy

The most apparent update is the Prius’s new 1.8-litre engine, lifting total output to 134bhp. It is hardly a breath-taking number, but the added shove makes motorway journeys considerably more restful, as the engine does not buzz quite so frantically. It should also deliver markedly improved economy on longer trips at higher speeds.

That is the theory, at least. We were not especially restrained with the accelerator, admittedly, yet achieved only 53.6mpg. That is very similar to what today’s fuel-conscious conventional diesels can manage. The additional power also raises a fair question: if fuel economy is the Prius’s overriding purpose, why alter the power output at all? Power has climbed by 24 per cent compared with the previous model, while fuel consumption improves by only 10 per cent and emissions by 14 per cent. The latter pair are undoubtedly moving in the right direction, but you cannot help wondering how much stronger they might have been had Toyota not pursued extra bhp.

Prius driving modes and on-road refinement

There are now three selectable driving settings: Eco, Power and electric-only EV. Swapping between them could scarcely be easier, thanks to buttons positioned beside the fly-by-wire CVT gear selector. ‘Power’ does exactly what its name suggests, making the accelerator less restrictive and overtaking far easier. It cannot match a diesel’s in-gear pull, but the Prius can now overtake without feeling as though it is about to explode. As before, the electric motor contributes torque during acceleration, then reverses its role under braking to become a generator and recharge the battery.

Select ‘Eco’ and it feels as if a tennis ball has been wedged beneath the accelerator pedal, although it does prompt a gentler driving style. Perhaps excessively so. Electric-only running is much too brief when pulling away from traffic lights in either ‘EV’ or ‘Eco’: apply anything more than the lightest pressure to the accelerator and the Prius beeps to say you are accelerating too aggressively, before returning to a petrol-and-electric combination.

The Prius has further shortcomings. Road noise intrudes far too much, while wind noise is also noticeable, though less severe. The steering remains devoid of feel, but perhaps that is not high on the Prius priority list. At least ride comfort is adequate on both the 17-inch wheels and the 15-inch alternatives.

Oddly, choosing the larger wheels rules out the solar roof, apparently because of weight and centre-of-gravity concerns. Then again, at £1,450 it is an extremely costly option, likely to appeal only to eco-warriors in Hollywood, where there is also sufficient sunshine to make it work. Standard equipment will include a head-up display and a considerably smarter cabin. The interior remains seriously practical, the central dashboard looks good, and there is the familiar assortment of clever, if slightly patronising, displays showing how efficiently and economically you are driving.

Yet none of that is really the point. Eco warriors with knowledge medals pinned to their hair shirts had begun to worry about the lifetime environmental costs of the earlier Prius, including the impact of its manufacture and shipping. Toyota is now keen to emphasise how much of the Prius is recyclable, including 95 per cent of the battery, its use of much cleaner energy at the Japanese factory, and the significant quantity of plant-based plastics now fitted to the car. Questions remain over the source of the battery’s nickel, but steel and iron must also be extracted from the ground, so ‘normal’ cars are not so different.

So, the new Prius is good. Simply driving it almost makes you feel that you are helping the environment a little. The old model had begun to lose that feel-good glow, but this version restores the shine. It is not entirely guilt-free motoring, but it is closer than ever before.