Right, here's a hypothetical question. You get stuck in the recent snow in your all electric car. You need heat, lots of it unless you abandon the car on the motorway and leg it. How long would it run the heater before being discharged, plus say the radio and screen demisters? I was chatting about this and as an experiment left a well serviced 1980's Volvo 740 idling with heater and blower on full, sidelights on and heated rear screen on. It had half a tank of fuel at the start of the test, so let's compare that with a half charged battery in the all electric vehicle. After 20 hours of idling the petrol tank was just under a quarter full still. Hmmmm.....
So, you are in the above scenario, your battery discharges completely and the car's stuck in the middle lane of a motorway when the traffic starts to move again. How do you charge the damned thing? Do the RAC / AA have some sort of generator or slave battery pack to get the thing off the motorway? A can of petrol or diesel that would give 20 miles plus after 20 seconds of pouring it in would be sublime in such situations...