I am confused about the clean air compliance. I am planning on renting (hiring) a car in Southampton using Alamo Rental. We are planning on driving to Bath, Bristol, Cotswolds and Oxford areas (amongst other places). How will I know beforehand if my car is compliant with the Clean Air Zone Requirements? The Bath website says "commercial vehicles such as taxis and private hire vehicles will have to pay".
Can someone clear this up for me
Nothing to worry about unless you're driving an old car. Your hire car will be quite new so exempt from any charges.
This is from Bristol council https://www.bristol.gov.uk/residents/streets-travel/bristols-caz/charges-and-vehicle-checker
but not from Oxford unless you are in a plug in EV, NOT hybrid.
Most folks pay £4 until this August, then it doubles to £8 per day. https://www.oxfordshire.gov.uk/transport-and-travel/oxford-zero-emission-zone-zez
well yes I'd pay £4 a day if I had the misfortune to visit Oxford again
see also https://www.gov.uk/clean-air-zones
if driving you are well advised to take advantage of Park & Rides