The automotive world used to be much more straightforward when the bonnet of a car either contained a petrol or a diesel engine. Performance, fuel economy, tax and various other costs all play a role when picking a motor. These days you can choose between plug-in hybrids and all-electrics along with frugal three-cylinder, downsized petrol engines and diesels with turbochargers. On the cusp of the electric transformation, manufacturers are coming up with all sorts of new ideas. Electric propulsio