Electric engines are great. They have just one moving part, the crankshaft. This means there is almost no friction, no temperature rise, not many fluids to move about. Today, an electric engine has somewhere from 90 to 95% efficiency rate. This means that if you put a hundred energy units to feed an electric engine, you get 90 to 95 units of kinetic energy out of the crankshaft. It is impossible to get efficiency rates higher than 100%, so there is no real room to improve electric engines. Sure, smaller and lighter engines would help, but the benefits would be in the handling and design department, not the efficiency one.
When it comes to electricity, the real problem becomes when you want to store it. I've look at a recent Audi e-Tron concept to know about some figures. Its batteries weigh 1.200 pounds and store the equivalent of a gallon and a third of gasoline. At this energy to weight ratio, you would need 9.000 pounds of batteries to store the equivalent of ten gallons of gas. That's 4 tons. Maybe it's not a matter of improving batteries a little bit. Maybe batteries for electric cars need to be 20 times better than they are now. Storing 10 gallons of electricity in just 500 pounds would be great. So, perhaps a new groundbreaking technology can do it, but today's tech is way too far from that.
Chassis and platforms for electric cars may be shared with their petrol counterparts, but they work much better if they are specific. Weight distribution around the car is the key to get good handling, traction and braking. Carmakers can design great platforms for electric cars, no doubt about that, but costs will be high unless they become as popular as petrol cars.
Up until now we've seen that costs are high and tech isn't quite ready. Carmakers can do R+D to achieve cost reduction and required specs. But there is a crucial question: Do they have to?
The answer is no. They don't have to. Batteries have improved a lot for the last 15 years, and cars haven't played a major role in there. Today, cell phones, tablets, laptops and power tools use batteries. We love electronic gadgets that run on batteries, and we all put the blame on them: they take ages to fill, but they only last a couple of days. If you don't abuse them, that is, because a hardcore user can run out of battery in just a few hours. We all know this. So do battery manufacturers.