2017 Toyota Prius Plug-in

If plug-in hybrids are to have a future after the laughable way they’re emissions-tested by the EU is corrected, and after the Government-funded incentives to buy one finally dry up, it seems to me they need to become two cars in one. They need the refinement, response, ease-of-use and zero-emissions capability of an EV around town as well as the longer-legged authoritative pace, range and drivability of a combustion-engined car on longer journeys.

It may have been different up until now, but with credible 250-mile-range electric cars emerging onto the market at affordable prices, duality will become absolutely key to the appeal of a good PHEV. Right now, most of them are better at one side of the equation or the other – and the Prius Plug-in is the same way.

Its interior is almost identical to that of a regular Prius except for the two-seats-only second-row seating. Its boot is smaller than that of its sister car on account of its battery positioning. On both fronts, with the likes of the Volkswagen Passat GTE available at a similar price point, we’ve reason to expect better material quality and practicality.

Away from its attention to the car’s hybrid powertrain, Toyota’s efforts have been spent on making the Prius Plug-in a more comfortable and refined car to drive than the regular hybrid. Noise and vibration insulation measures have been added under the bonnet, inside the front wings, under the interior carpeting and around the rear wheel arches, while the car’s suspension springs, dampers and anti-roll bars have been retuned for greater compliance.

The rewards are just about noticeable, though you still wouldn’t call the Prius Plug-in a refined car to drive in outright terms. It rides with more suppleness than the regular Prius, but its chassis still thumps and rumbles away a bit over poorer surfaces. And while the powertrain’s predictably quiet under electrical power, the petrol engine’s tendency to rev away noisily to its redline when you use anything more than about 50% of the accelerator travel remains a discouraging, nannyish bugbear.

Up to about 50mph, progress feels strong in electric-only mode. The Prius Plug-in has more than enough power and torque to keep its combustion engine quiet and responds to the pedal in the super-keen, linear proportion you want from an electrified car. The brake pedal's feel is the familiar muddled jumble of regenerative force and sudden apparent friction that makes slowing the car smoothly an exercise in guesswork. Yet you can still enjoy the Prius Plug-in’s hushed flit around urban roads – while it lasts. Toyota’s 39-mile electric range claim isn’t to be believed; repeated testing suggests that the car’s actual electric autonomy is more like 25 miles, which is good, but not exceptional among PHEV rivals.

Once the Prius Plug-in's lithium ion drive battery is depleted and you’re beyond the bounds of the city, the car takes on a dynamic character indistinguishable from that of a regular Prius – albeit one with an extra 130kg to lug around. On A-roads and dual carriageways it’s slow and somewhat alienating under acceleration. Along twistier stretches it handles competently but with familiar remoteness. Its standard 15in wheels and 65-profile economy tyres running out of grip quite frequently - and quite suddenly - if you try to keep up a head of steam.

Drive more conservatively, as Prius converts undoubtedly will, and your reward is hybrid-mode fuel economy in the high-60mpgs: a far sight better than most PHEVs will return, but also only about 5mpg better than you’d get from the regular Prius.

The Prius Plug-in may be good enough to convince a minority of buyers that Toyota offers the best PHEV, but it’ll do little to endear the breed to a wider audience.

It has taken Toyota four model generations and twenty years to bring the regular Prius to a point where you might say it’s finally good enough, in most important ways, to seamlessly replace a conventional £24,000 hatchback for the average driver. But by adding £10,000 to that car’s price tag, beefing up its electrical reserves but doing little to the rest of the package, Toyota has promoted the Prius way beyond its abilities here, and stretched its credibility as a product much too thinly.

As far as the sweeping history of electrified motoring goes, I’m afraid this is a sideshow; a footnote; a car that fulfills its own limited brief, and will work well enough as a bridging platform for a few thousand very particular European customers every year who aren’t quite ready to take the plunge with a full EV. But compared to the hybrid state of the art – the latest-generation petrol-electric offerings from the European car-makers who’ve spent two decades trailing in Toyota’s wake but are now in a position to go toe-to-toe with it – it’s weedy and one-dimensional.

There should always be a place for daydreaming amongst the people who design and engineer our cars, but where Toyota’s hybrids are concerned – for the next few years, at least – a bit more benchmarking might serve the company better.

Toyota Prius Plug-in

Location Barcelona, Spain; On sale now; Price £34,895 Engine 4cyls in line, 1798cc, Atkinson Cycle petrol; with dual-motor hybrid assist Power 121bhp at 5200rpm; Torque not specified Gearbox e-CVT; Kerbweight 1550kg; 0-62mph 11.1sec; Top speed 101mph; Economy 283mpg; CO2/tax band 22g/km, 9% Rivals: BMW 3 Series 330e, Volkswagen Golf GTE