Rolls-Royce chief Tom Purves has told Car Magazine that he thinks his firm might build a battery-powered version of its Phantom limousine. “Many of our customers do small mileages exclusively in the city - for these customers, an electric Rolls-Royce would be ideal,” he told the mag.

Small mileages might be the only option. Given that the 5.8-metre-long limo weighs 2.5 tonnes (including its current 6.7-litre V12 engine) it would need lots of energy and thus a truly gargantuan battery to get it moving.

Apparently Rolls-maker BMW intends to apply lessons learned from its Mini E electric car project. But that car sacrifices half its passenger capacity to make room for a bumper box of lithium-ion cells. Somehow we doubt that a Phantom with no rear seats would be in much demand as city transport for the well-heeled greenie.

There is precedent for this madness, however. UK-based Liberty Electric Cars is converting Range Rovers to run on electrical power, starting with a car that weighs about the same as the Phantom (and which shares the same RR initials, too). Liberty claims a range of 200 miles. We don’t think anyone impartial has actually driven one of these beasts yet, although you can order one if you’ve got £95,000 to £125,000 eating a hole in your trousers.

On Monday, government officials and industry experts will get together to see if they can work out how to promote the growth of electric cars in the UK. Ahead of the meeting, business minister Ian Pearson said, "Currently, less than 0.1 per cent of the UK's 26 million cars are electric ... We need to act now to ensure that the UK is at the forefront of this new industry. The development of electric vehicle technology is an opportunity for the UK to take the lead and, given the state of the global economy, we need to seize that opportunity."

Pearson’s figure, low as it is, probably inflates the UK’s electric car fleet by a factor of ten. According to Reva, maker of the world’s most numerous electric car, about 1,000 of its G-Wiz runabouts are currently on UK roads, which is about 0.004% of the 26 million. We suspect the real total, including milk floats, probably totals less than 0.01% - or one in 10,000.

Far be it from us to pre-empt Monday’s discussion, but money always helps. Earlier this month the French government pledged €400m (about £310m) to help carmaker Renault and French energy firm EDF get a nationwide recharging network off the ground by 2011. Other countries, including Italy and India, continue to offer financial incentives to buyers of electric vehicles, whereas the UK’s PowerShift grant programme evaporated back in March 2005 - when oil still cost less than $50 a barrel and if you bought a Prius people were prone to whisper “Should have gone to Specsavers” behind your back.

According to Chetan Maini, chief technologist at Reva, the one thing EV entrepreneurs want from governments is long-term certainty about any incentives. It doesn’t matter if there is a timetable for removing a tax rebate, he told us recently, as long as that schedule is clear and, preferably, that the phasing out is gradual. Playing fields that tip suddenly and without warning – like Ken Livingstone’s political twisting of the London Congestion Charge, thankfully scuppered by his successor – tend to send investors running.

So whatever the horse-traders come up with on Monday, let it be something with legs, please.

We know that the much-anticipated Chevrolet Volt will spawn a European cousin based on the Opel Flextreme concept car, built around the Volt’s E-Flex petrol-electric technology and using the platform from the next Astra/Zafira.

And we know also that General Motors has talked about the possibility of bringing the Volt itself to Europe (no doubt to left-hand-drive markets). But to date we haven’t been told what either of these cars might be called in the UK. Vauxhall Volt does have a ring to it, of course, but does Vauxhall Flextreme?

Names are a small point but, we feel, an intriguing one. So we note with much interest that General Motors UK has just applied for a trademark on the name “Vauxhall Electra”.

This move is, we feel, surely too much to be a coincidence.

BMW will show off an electric Mini at the upcoming Los Angeles Auto Show, and will lease 500 of the battery-powered beasties to interested individuals or businesses in California, New York and New Jersey in 2009.

The Mini E is clearly a bit of a bodge job, and is probably more about PR and fact-finding for BMW than a serious transport proposition. The lithium-ion battery takes up what used to be the rear passenger seat area, for example.

The battery is interesting. We’ve read rumours that it might be related to the Tesla Motors power pack, since it is constructed from a large number of small cells assembled in sub-units. However, the numbers suggest that the two are not related. Tesla uses 99 bricks of 69 cells each to give its Roadster a total of 6,831 cells. BMW has used 48 units of 106 cells each to give the Mini E its grand total of 5,088 cells. Similarly, Tesla claims 56kWh total energy storage, while the BMW quotes 35kWh - giving the German runabout a much lower energy density per cell.

But while the battery is different, the thinking behind it is not. BMW is thus likely to gain large-scale data about the viability of the big-box-of-batteries approach at the same time as, or perhaps ahead of, its upstart electric car rival.

The Mini E also bears no resemblance to the electric Mini concocted by PML Flightlink to show off its compact in-wheel motors. BMW’s new baby uses just the one motor to drive the front wheels through a single-speed gearbox.

Meanwhile we are left to speculate about whether the Mini E will come to Europe. BMW UK seems to think it likely, but has no dates or real plans to talk about.

We’re also left wondering if this is the electric car that BMW top brass began murmuring about in February, triggering much speculation about a third brand and sub-Mini city cars. If it is, it’s a bit of a let-down. But then, as we said above, the Mini E is clearly a case of research in progress. Let’s hope the experiment bears worthwhile fruit.

Italian industrial group Tazzari is gearing up to produce its own electric car, and today released the first clear image of the thing. The firm had previously provided a somewhat annoying teaser video. The new picture of the Tazzari Zero looks a little on the computer-generated side to us, but then the real thing is not due on the road until next year.

The teaser video gives a few specs: 542kg weight, 90km/h (56mph) top speed, 150km (93 mile) range, 0-50km/h (31mph) in 5 seconds, all of which seem like reasonable claims. The stated 45-minute recharge and running costs of 1p per mile will require an industrial three-phase supply and some creative accounting, respectively. The batteries are to be lithium-based.

Today Tazzari added that the Zero’s electric motor is “centrally positioned” – we hope the batteries are too if the aim is for mid-engined balance and manoeuvrability. It will also be rear-wheel drive.

Tazzari Group specialises in cast aluminium, so it’s no surprise to learn that the Zero will boast an aluminium frame with, presumably, plastic panels. There are no details yet on price or availability.

In stance and proportions it reminds us a little of the MyCar, which also boasts Italian style but is made in Hong Kong and and is currently a slower and probably cheaper option. The Zero will in fact be sold alongside the MyCar in the UK by the Nice Car Company.

Quite a bit of size, and quite a lot of quirkiness, has been lost in the translation of Venturi’s Eclectic electric car from concept to production form. While the Eclectic concept looked like something burped up from the belly of a UFO, the finished edition looks like it’s just driven off a golf course.

The original design was clearly the result of form through function. Designed to be energy self-sufficient, it needed a broad, long canopy to offer the maximum area for solar panels – dictating the Eclectic concept’s generous proportions, upright glass, and wider-at-the-top frame.

The finished car keeps the details of the larger design but loses the proportions. As a result it’s unlikely to be energy self-sufficient, sadly. According to Venturi, the new car’s 0.8 square-metre photovoltaic panel offers less than a third of the concept’s sunlight-gathering potential. It will peak at 70 watts and provide only enough power for 2km (one and a quarter miles) per day. And that’s if the driver can leave it in a sunny spot - underground car-parks, leafy avenues and domestic garages will not be good places to park your Eclectic. A 300-watt wind turbine is also an option that, on a windy day, will generate enough juice for about 13km (eight miles). Most driving will, therefore, be powered by electricity that comes out of the wall – a full charge of its Trojan batteries takes five hours from a 16A socket.

Production will start in October 2009, but Venturi is taking reservations now. It aims to build 3,000 units per year. Legally the finished Eclectic will be classed as a heavy quadricycle, the same category as the G-Wiz and Mega City electric cars. The quoted range is 50km (31 miles) with a top speed of 45km/h (28mph), and it will cost from €15,000 (a little under £12,000). Doors are presumably extra. Overall, we feel these figures will not be causing any sleepless nights among the competition.

All in all, the production Eclectic seems an underwhelming prospect after the lunar-module loveliness of the enticing concept. Given that it will struggle to best today’s production electric cars, how will it make any kind of sense against the upcoming Think City and Pininfarina B0?

Pininfarina’s upcoming B0 electric car (that’s a buzzy, efficient bee-zero, not a whiffy bee-oh) is a wonderful thing, and not just because it looks as perfect as a swallow’s egg from every angle. One might expect the Italian styling house responsible for oodles of Ferraris and the Talbot Samba Cabriolet, no less, to turn out a pretty little thing but no, we love the B0 because it aims to put supercapacitors on the road.

The supercapacitors, along with lithium metal polymer batteries, come from the less glamorous half of the partnership behind the B0 – BatScap, part of French electronics group Bolloré.

Unlike batteries with their caustic chemicals and exotic materials, capacitors are conceptually simple things – not much more than a bucket in which to store electrons. At their most basic, capacitors are made from two metal plates with a gap between them, across which electricity is not able to jump. Apply a voltage to the plates from a dynamo or battery and the electrons will gather, like penguins at the edge of an iceberg worried about hungry seals in the water. Remove the generator and leave the circuit open and the electrons will happily stay put for quite a while, their energy held in an electric field. Connect a load – like a motor, say – and the electrons will flow back away from the edge, providing a quick burst of eager electrical energy.

In practice, in most ordinary capacitors, the two metal plates are made from sheets of metal foil, separated by an insulating film (called a dielectric) and rolled up tight in a tiny tin can. The larger the surface area of the foil, the closer they are together and the better the insulator between them, the more energy can be crammed into the capacitor before it starts to leak significantly around the edges and across the gap.

Supercapacitors do the same job only more so – sustaining bigger electric fields and a greater density of electrons. Enough, in the case of the B0, to provide worthwhile motive power.

In the B0, the supercapacitors are put to a specific use – storing energy from the regenerative braking system, and immediately feeding it back into the drive system when the car accelerates again.

This is an ideal role for a capacitor, and a much better fit for the job than a battery. Batteries degrade over time, their chemicals gradually falling to pieces over a few tens of thousands of charge-discharge cycles. But capacitors don’t suffer the same degradation. Keep within tolerances and they can, in most cases, happily charge and discharge through billions of cycles. Ideal, in other words, for stop-start city traffic where it seems possible to slow down and speed up an infinite number of times on the way to work.

Capacitors are also fundamentally more efficient than batteries at short-term storage of electrical power, due to the fact that there are no gross energy transformations involved. In a capacitor, electrical energy goes in, is stored in electrical form, and electrical energy comes out again. In a battery, by contrast, electrical energy is converted backwards and forwards through chemical reactions, with associated inefficiencies and heat losses.

Capacitors are also able to store energy in much more rapid bursts than batteries, suiting the short-but-intense role of transforming kinetic energy into stored electricity during sharp braking.

The bottom line? A supercapacitor-equipped electric car ought to go a fair bit further than an equivalent runabout equipped with batteries alone. And that expensive battery pack ought to last a lot longer to boot.

So while we love the fuss-free look of the Pininfarina B0, we really love the nitty-gritty details of its BatScap-built underpinnings.

Honda provided some nice video of its new Insight hybrid concept, but without any sound. So in the absence of any whooshing, driving-up-the-road noises we've set it to music - a track called Star City by Alpha Seven. Enjoy.

This car is bad news – if you’ve just bought a Toyota Prius. The 2009 Honda Insight looks like a Prius, will no doubt drive a bit like a Prius, probably isn’t as clever or as frugal as a Prius, but nonetheless and most importantly is considerably cheaper than a Prius. It’ll start from around £15,000 when it goes on sale in the UK next spring, so if you’ve just plonked down 18 to 20 big ones on a slippery eco Toyota, you may find your resale value just took a dive. After all, in a couple of years’ time what would the average punter rather buy, a brand-new Honda or a second-hand Prius with baby-sick stains on the back seat?

Prius hawkers may draw your attention to superior fixtures and fittings like the (mostly useless) robotic parking facility or other electrified gewgaws to justify the extra requirement of readies, but the long and short of it is that resale values of Priuses will plummet by an extra couple of thousand the moment the Insight goes on sale. We wouldn’t be surprised if Toyota was forced to trim the RRP of new Priuses, for that matter.

When it all shakes out, the Insight’s arrival will be excellent news for second-hand Prius buyers. That’s not to knock the Insight. We love the look of the Honda, and it will no doubt be a lovely thing to drive and a plasticky thing to sit in. But we think that Toyota’s Synergy Drive hybrid system is a superior set-up to Honda’s Integrated Motor Assist. At least as fitted to the current Civic IMA, the Honda hybrid combination is not as fluid as the Prius in stop-start traffic and less good at saving petrol around town.

So hurrah for Honda but we’ll take a one-prior-owner Prius, thanks. The baby-sick stains will probably come out with a bit of Cillit Bang.