Yeah I'm skeptical of the 300km range too, though it does look like a very small and light car.
And unless the electricity is being provided by a renewable energy source, this is actually worse than burning fossil fuels directly.
Fossil Fuel -> Car is going to be more efficient than Fossil Fuel -> Electricity -> Compressor -> Air -> Car
And the compression / decompression stages are very lossy.. compressing the air will generate lots of waste heat, though using it will cool the air which is great for A/C
