Details specific to the model include silver accents on the door handles, model-specific five-spoke 15-inch alloy wheels and a Plug-in Hybrid logo on the front wing. At the rear the LED lamp clusters have clear lenses and the trim above the licence plate has a silver finish. The Hybrid Synergy Drive badges incorporate a plug-in symbol.

Details specific to the model include silver accents on the door handles, model-specific five-spoke 15-inch alloy wheels and a Plug-in Hybrid logo on the front wing. At the rear the LED lamp clusters have clear lenses and the trim above the licence plate has a silver finish. The Hybrid Synergy Drive badges incorporate a plug-in symbol.

Toyota is currently rolling out the latest addition to the Prius hybrid family – the Prius Plug-in. How does it differ from the standard Prius hybrid?

In essence, it costs a little more to buy (with grant, in UK) and you can charge a more sophisticated battery pack (lithium-ion, for better performance and recharge) from the grid with the result that you have a higher range in EV-only mode.

The range in electric drive mode is not huge, but 15.5 miles will be sufficient for many urban journeys and is considerably better than the 1.2 miles on the standard Prius. Toyota says it came up with the 15.5 mile range after the feedback received from a five-year long global PHEV trial, so that the car has best compromise on range, performance, packaging, vehicle weight and price. It is claimed that the 15.5 mile range is sufficient to meet the daily commuting requirements of 80% of Europeans.

So, you can have a compromise workable EV, but without the range anxiety, because Toyota says that the Prius Plug-in gives you well over 700 miles of range once the 1.8 litre gasoline engine kicks in.

Let's be clear though. Prius Plug-in is not a replacement for the standard Prius, but will be offered side-by-side with the current model for the foreseeable future. Toyota can continue to provide the standard model - with its nickel metal hydride battery pack - at a much lower price than the new plug-in. Toyota product manager Neil Spiers see Toyota offering a suite of electric drive vehicles according to specific needs. “This is a family-sized vehicle that meets certain performance criteria and comes at a certain price point; it's about the package and the benefits we can provide through developing such a vehicle with its plug-in hybrid set-up,” he says. “But the other models in the Prius family also play a part in meeting specific needs.” And there's an iQ EV prototype that suggests Toyota is well aware of the potential growth for short-range EVs in cities. Flexible response. Horses for courses. Call it what you will, but many manufacturers are now recognising the importance of having a range of powertrain offerings to meet changing market needs and regulatory frameworks across the world. If you can afford it.

Right now the Prius Plug-in targets look modest. In the UK market, sales this year are planned at around 1,300 units, with a rise to 1,600 in the first full-year of sales next year. The standard Prius sells at around 4,000 units a year, a figure which Toyota does not expect to change significantly. Toyota expects the car to attract early adopters and conquest purchases from people looking for something a little different. Fleet users are in Toyota's sights given the headline low 49g/km of CO2 and the taxation benefits to company car drivers.  

The Prius Plug-in is being positioned as a premium product (a single equipment specification that includes LED headlights, touchscreen controls, rain-sensing wipers, eight speaker JBL sound system...) within the Prius family. The car’s EV range and its ultra-low CO2 emissions mean that it qualifies for the UK Government’s Plug-in Car Grant, which reduces the vehicle purchase price by GBP5,000. It still comes out at GBP27,895 though and that's GBP3,000 more than the standard Prius in its top of the range T Spirit spec. If that grant wasn't there for some reason, a 'real' price of GBP32,895 illustrates how relatively expensive this technology currently is (the T3 spec standard Prius hybrid comes in at GBP21,600). However, plug-in and lithium-ion power pack unit costs should fall in time as volume rises and that could well mean that the plug-in/standard-hybrid mix sees more plug-ins eventually.

Prius Plug-in has three on-demand drive modes: HV, EV and EV-City. When the driver selects HV (hybrid vehicle) mode, the car operates in much the same fashion as the standard Prius, with the Hybrid Synergy Drive system seamlessly engaging the petrol engine when required. When EV mode is selected, Prius Plug-in can draw on the hybrid battery’s full capacity and will remain in electric drive mode for urban driving with minimal noise and zero tailpipe emissions for up to about 15.5 miles, at speeds up to 51mph. The petrol engine will start up if the system judges that extra power is needed, but using light to medium throttle inputs will keep it switched off throughout EV mode operation. With EV-City mode, Toyota says the characteristics of EV mode are matched, but more forceful use of the throttle can be made before the petrol engine kicks in, allowing drivers to use the car in inner city zero emission zones.

Eco mode can be activated independently, when the car is running in HV, EV or EV-City modes. In any drive mode, throttle response to the driver’s use of the accelerator pedal is reduced and the air conditioning system is adjusted to achieve better fuel economy. Depending on driving conditions, this can help drivers achieve a noticeable reduction in fuel consumption, Toyota claims.

It's hard not to be impressed with the technology and investment that Toyota applies to its hybrid products. In focusing on PHEV technology, Toyota says it has addressed the matters of driving range, cost and infrastructure that act as inhibitors to pure battery electric vehicles.

In creating the Prius Plug-in, Toyota has gone with a relatively heavy lithium-ion battery (they have higher power density than nickel metal-hydride, so the added mass is for higher capacity on the plug-in). Its kerb weight is 1,450kg, 50kg more than its standard sister model, and the weight of its lithium-ion battery is 80kg, 38kg more than the nickel metal-hydride battery in the standard Prius. The battery can be charged quickly though – Toyota says in an hour and a half.

Total system output from the Hybrid Synergy Drive powertrain is 134bhp (100kW), giving 0-62mph acceleration in 10.7 seconds and a 112mph top speed. The car’s extended EV range significantly enhances its overall fuel efficiency, Toyota claiming an official figure of 134.5mpg, an improvement of 45% on the performance of the standard Prius. Average CO2 emissions are put at 49g/km, and levels of NOx are much lower than from diesel engines with comparable performance, Toyota points out.

Once the limit of its EV range has been reached, the Hybrid Synergy Drive system still returns combined cycle fuel consumption of 76.4mpg and 85g/km CO2 emissions, Toyota claims. These figures remain lower than those of the regular Prius due to the fact the new lithium-ion battery used in Prius Plug-in can recover energy under braking more efficiently, recharging the battery more quickly and enabling greater use of the car’s EV mode. In addition Prius Plug-in is fitted with the latest generation of low rolling resistance tyres.

The battery pack used for Prius Plug-in has been developed by Toyota in a joint venture partnership with Panasonic EV Energy. Its capacity is 4.4kWh – almost four times greater than the battery in the standard Prius – and its state-of-charge for use has been improved to about 60%.

I didn't actually see this in action on the drive, but Toyota says that drivers can visualise the benefits of external charging by a 'novel forest display'. The system converts the amount of electricity sourced from external charging into a reduction in CO2 emissions. For every 10kg saved, one tree is planted in the forest. As the number of trees increases, flowers and animals are also added to the display. I can imagine getting a mild kick out of keeping an eye on that.

What was it like to drive? Basically, no different to a standard Prius. Moving off in EV mode, progress was fine. Switching to the other modes was easy. If felt like a heavy-ish car, but it is very quiet, and not only in EV mode. There is a lot of info for the driver to take in on the display, but I was told the typical Prius customer wants all of that and to play with the modes, maximise fuel economy and, I guess, save a few more trees. The busy display can be simplified if you want.

You will pay a fair bit more for the Prius Plug-in over the standard Prius model and there is no getting away from that. It's a leap. There are significant benefits though (especially on company car benefit-in-kind tax) and I would be surprised if the modest sales targets in the UK weren't met while there is a GBP5,000 government grant. I'd also be surprised if the plug-in share of Prius sales didn't rise substantially over the next five years, provided the initial volume targets are met and prices gradually come down. 
 
Toyota is certainly committed to hybrids and says it will continue to bring new hybrids to the European market, with its range growing to around 10 models by 2015 and extending to most of its range as early as possible in the 2020s.