For me (not driving that many miles being retired) the economics look shaky.
The compressor is in the 4 grand range and the Honda Civic Nat Gas version is about 6 grand more.
My fuel cost currently is about $1500/year so even if I cut that in half the payback is quite lengthy.
NG would be a nice hedge on availability if for some reason gasoline is a problem. I’m old enough to remember the fuel problems of the 70s in the Nixon and Carter era.
That is going to be key with any up front cost for lower cost to drive.
I'm averaging 20k a year on my truck and about 50k including the other two vehicles. But the oldest heads away to college in the fall.
I've considered it. But I haven't justified it yet.