Go for the standard Prius model with its old-tech nickel metal hydride battery and you'll find that it doesn't go very far on battery power alone. From start off, it's great fun to waft around in virtual silence, but you only need to have gone a mile or so down the road before the petrol engine thrums smoothly into life. This Prius Plug-in model is different. It gets a more sophisticated lithium-ion battery that can be charged from the mains, a unit that's twice as large in this second generation model, its capacity having increased from 4.4 to 8.8kWh. The downside of that is a 50% increase in battery weight, but thankfully, the bulk has been mounted very low down in the vehicle, which helps keep an admirably low centre of gravity.
All-electric driving range is rated at around 34 miles, though you won't get anything like that if you start to really use the increased EV power of this MK2 model. This has risen by 83% thanks to a new Dual Motor Drive System that boosts EV driving power to 68kW, giving better acceleration and more engaging performance. The handling's more engaging too, thanks to this second generation design's use of Toyota's New Global Architecture platform. This stiffer set-up reduces bodyroll and improves refinement.
This second generation Prius Plug-in model is longer, wider and lower than its pre-2018 predecessor, just like the standard self-charging hybrid variant. Distinguishing Plug-in aesthetic touches include prominent acrylic grille treatment at the front and thin, ultra-compact four-LED adaptive headlamp units. In profile, this variant gets a longer rear overhang, a lower cowl and a rear spoiler, plus special two-tone 15-inch alloy wheels that are specific to the model and are designed to provide extra brake cooling. At the rear, the cross section of the distinctive Prius 'double-bubble' screen is carried through into the curve of a spoiler flanked by unique LED light clusters.
Inside, there are fewer changes over the standard Prius, though Plug-in buyers do get smarter satin chrome-plated trim, while the dual 4.2-inch TFT meter in the revised instrument panel features PHV-specific graphics. Otherwise, the dash is very similar with a clear structural arrangement of layered information which places the driver's meters at a distance and the displays closer at hand. A large eight-inch infotainment screen dominates the centre of the fascia. The front seats too, are shared with the conventional Prius, offering improved cushion comfort to reduce driver fatigue. In the rear there are two seats separated by a centre console. Out back, the luggage deck has been raised by 160mm to accommodate the larger plug-in hybrid system, resulting in a maximum loadspace volume of 360- litres. That's 142-litres less than you'd get in the conventional model.
Expect to pay quite a premium for Prius Plug-in motoring over what you'd have to find over the conventional version of that car. We're talking around £5,000. Also making this variant look expensive is the fact that it only comes in the two plushest levels of Prius trim - 'Business Edition' and 'Excel'. What it all means is that you'll need just under £33,000 for a 'Business Edition' Plug-in model - and around £2,000 more than that if you want the top 'Excel' variant.
At least the car will me very well equipped for that kind of money, with nearly all the executive toys you would want. The key changes made to this improved model lie with the addition of 'Lane Trace Assist' to the car's standard portfolio of 'Safety Sense' active safety and driver assistance systems. 'Lane Trace Assist' operates with the full-range 'Intelligent Adaptive Cruise Control' system, helping the driver keep the car centred in its traffic lane. Using the forward-facing camera and millimetre-wave radar, it monitors lane markings on the road surface. If it detects any unintended deviations, it will provides gentle steering inputs to keep the car to its correct course, both on straight roads and through curves. If the markings are faded or obscured, it will follow the path of the vehicle ahead. This latest Prius Plug-in also gets 'Apple CarPlay'/'Android Auto' smartphone-mirroring (at last); and owners can now use the Toyota 'MyT' app. This incorporated eCall to provide an automatic alert to the emergency services in the event of a serious impact. Other 'MyT' app features include useful information about Toyota, service alerts, "find my car" vehicle location, journey planning and coaching on how to achieve the best eco-driving performance. MyT also logs driving data, so information about mileage, speed and performance from previous journeys can be accessed and analysed.
If you've had a cup of hot, sweet tea to recover from the asking price of the Prius Plug-in, the rest of this section may well help with its restorative effect. As with other plug-in vehicles, quoting a miles per gallon figure for the Prius is largely academic, because in certain scenarios the figure is effectively infinite. Toyota has nevertheless jumped through the hoops of the WLTP test and quotes a combined cycle figure of up to 235.4mpg for this Prius. The emissions figure of up to 28g/km is also open to a bit of debate, but it spells huge tax savings, so who's arguing? Insurance is group 20E.
Maximum charging power in this MK2 model is rated at 3.3kW. The battery can be fully charged up to 65% quite quickly - in just two hours using a Type II Mode III Mennekes connector, or three hours 10 minutes using a standard household plug socket. The charging process can be programmed for a week on a day-to-day basis, including the facility to simultaneously charge the battery and pre-heat or pre-cool the cabin. Toyota has also developed solar charging panels for the roof which can charge the battery to a small extent when the vehicle is parked up in the sun. This, the company says, would increase the car's EV driving range by up to around three miles every day - the equivalent of 620 miles of all-electric driving in a year.
Is this logical extension of hybrid technology the future of motoring? Probably not - but it's an important step along the way. It won't be very long before Plug-in technology is the preferred route for hybrid buyers - at which point you'd hope for more cost-effective pricing.
But would you buy one of these today? We think a significant number of Prius owners might. Now that the Prius Plug-in has a credible driving range, is easier to charge, has a bit more EV power and is better connected, it makes some sort of sense as an everyday proposition. Ultimately, as before, this Toyota is aimed first and foremost at Prius people and we don't doubt that those who can afford it would love one. Whether it can reach out for broader acceptance beyond these folk will depend largely on whether the whole concept of Plug-in hybrid technology continues to capture the public's imagination. We wouldn't bet against it.