Very very few LNG cars and trucks out there, as filling infrastructure is limited compared to CNG. In US it's something like 2% of total CNG+LNG fleet.

Interviewed with a midwestern company doing CNG truck conversions and building fueling infrastructure back in 2014/15. Diesel prices coming down crushed them, and they sold off the majority of their fueling station biz in 2019, to focus on renewable CNG from dairy & hog farms.

I was confusing it with LPG. The huge majority of buses and taxis around here run on it, which is a big percentage of traffic on the road. A decade ago it was 100%, now most new replacements are electric but it will take at least another decade until the existing LPG fleets are entirely replaced.

I once drove a shuttle that ran on compressed natural gas from the airport, but liquefied sounds more demanding to handle.

You may be thinking of LPG, which is a mix of propane (three carbon atoms) and butane (four carbon atoms) and it's a liquid under reasonably low pressures. LNG is pure methane (one carbon atom) and you have to cool it to -163 degrees C to make it liquid. I don't know of any land vehicles that would use LNG as a fuel. Normally it's just transported in enormous LNG tankers by sea to import (regasification) terminals and then fed into the grid. The comparison with coal is quite apt, because one of the main selling points of LNG is that it displaces coal in terms of power generation and as an industrial feedstock.

There's also CNG which is compressed natural gas, and that's (largely) methane but it's a pressurized gas not a liquid. That is sometimes used in heavy goods vehicles.

You're correct, I was thinking of LPG.