We had a compressed-natural-gas-for-automotive-fuel system (CNG) here in NZ in the 70/80s, and I had a car which had it as alternative fuel.
Natural gas gives noticeably less power than petrol, and in this installation, particularly pick-up acceleration.

I was less than impressed. After a couple of incidents where I forgot which fuel I was using and tried to accelerate through a gap in oncoming traffic, and instead CRAWLED through the gap to horn accompaniment, I removed the CNG installation.

Another problem, in this installation, was that the car was a station-wagon, so the (large, heavy) tank was inside the load space, and right over one rear wheel at that! The installers had fitted an extra leaf in the spring on that side, and adjustable shock absorbers as well, but it upset the handling of the midsize european car so much that I lost trust in its ability to swerve in an emergency.
Afterwards, my wife drove the car until it died. It became her 'favourite-ever.' 'Judy's Red Rocket.'
So, I'd suggest that CNG should be fitted only to specifically-designed cars, and as the only fuel, but that opinion is based on one aftermarket installation. Your authorities could also benefit by consulting the NZ experience. I haven't seen a CNG filler pump for many years.
We also have dual-fuel vehicles using LPG, liquified Petroleum Gas, which is much more powerful. Most fork-hoists use LPG, and it is also used for camp stoves and is readily available.