Lots of the electric cars that'll soon be rolling through production lines and out on to the roads may not look much different from gasoline-powered cars from the outside, but there are a variety of design considerations that can really bring new possibilities to the way that cars are designed. Let's look at a couple of those.
The image on the top right of this post shows the back end of a Tesla Roadster electric car without the body panels. The metallic cylinder in the middle is the electric motor. It's not much bigger than a watermelon, yet it can accelerate the car from 0 to 60 miles per hour in less than 3.7 seconds, leaving behind many exotic sports cars. It weights less than 70 pounds and generates 288 horsepower (215 kW) and 200·ft-lbf (270 N·m) of torque.
To get equivalent performance from a gasoline or diesel vehicle, you would need a much bigger and heavier engine.
electric car drivetrain photo
The photo above shows electric car batteries. While the electric motor is smaller than its fossil-fuel counterpart, the batteries are bigger than a gas tank. On the other hand, they can be spread over the vehicle in innovative ways. Many of the first electric cars won't take full advantage of this, because they are based on cars that were originally designed to be fueled by gasoline. But as time goes on, car engineers and designers will no doubt create automotive platforms that take full advantage of this to make well balanced cars (a good weight distribution leads to better handling) that provide maximum cabin space for passengers.
These are two big differences with traditional cars that will influence the design of electric cars over the next decades.
This isn't to say that these things automatically give an edge to electric cars, at least not right now. Modern EVs are still in their infancy... But if we have a bit of vision and look ahead, we can see that the maybe disadvantages of EVs (cost, range, weight) will progressively be fixed by progress in battery and hypercapacitor technology, while the advantages of EVs will only become more important to society (no tailpipe emissions and they can be powered by a variety of sources including clean and renewable ones).