When travelling to the UK, I usually book a car through the Avis/BA website and get a much better deal than going through Avis.com

This is the rate I have for a nine day rental from LHR next week:

Car group: Group F ( e.g. Vauxhall Insignia)
Please note AVIS is confirming a car group and not a specific model or
engine.
Price : 272.47 USD (or £170)

210,62EUR
Your quote includes:
Local Tax (TAX)
Vehicle Damage Cover* (CDW) -
Vehicle Theft Cover* (TP) -
Vehicle Registration Fee (VRF)
Airport/city/other surcharge
Unlimited Mileage
Please note - although the cost is displayed, if you are an Executive Club
Member you will receive one free additional driver per rental as part of
your partnership benefits.

Not sure about the US, but this covers most except for the high deductible or excess - I take out the additional coverage.

If I booked though Avis Car Hire UK, the exact rate and quote would be £385.73 or $616!
So to answer your query - IMHO I think you are on the right track with AVIS/BA