"take that on a motorway and you may as well be signing your own suicide note."
It'd probably handle a steady 56mph quite nicely, same as all the lorries on the motorway, so not really a huge problem. In fact, sitting behind a lorry at a normal distance will even help on the fuel economy.
What a lot of people seem to forget is that the various alternative propulsion and fuels tech is still in it's relative infancy and the early adopters are most likely to be those most wanting to "save the planet", not the petrol heads with lead feet. Those people will already be driving the most economic IC engined cars they can find and doing so in eco mode to get the best mpg they are capable of.
Tesla are beginning to break that early adopter stage and aiming for a more mass market but that comes at a relatively high start-up cost for the consumer.