Good info. Thank you.

Electric vehicles were deemed 'impossible': now the streets of London are full of them (built in Bangalore, retail for £8000 each).  

And the roads are full of Toyota and Honda hybrids which are electric vehicles (at urban speeds).

In the early days of automobiles, the steamer car looked like a real competitor.  To kill them off, the internal combustion engine makers had to pull some very dirty tricks (commissioning articles about car boilers exploding), the Stanley brothers were very uncommercial, and there was an outbreak of foot and mouth disease one summer (closing all the cattle and horse troughs, so no water to refill).  A steamer would probably run CNG much more efficiently than an ICE car?

The key was all these alternatives were to some extent 'purpose built'.

Whereas CNG vehicles are simply converted ICE vehicles.

I wonder if by actually building from the ground up a CNG vehicle, we could get much improved performance and range?