I've noticed the decline as well. At my old company I rented from Avis all the time up until about 18 months ago when the amount of my business travel was reduced to almost none at all. During the four years I rented from Avis regularly (2000-2004) I never had a problem. I never had a dirty car, never had a car with more than about 12,000 miles on it, never had a car with a major dent or scratch.
Then I changed companies earlier this year. My new company was using National, and I quickly fell in love with being able to pick my own car. All of the National cars I rented between April and June of this year were very new (fewer than 10,000 miles) and extremely clean. Most of these rentals were at major airports (PHL, SEA). In June we switched to Avis. Fine, I thought, I've done the Avis thing before and it was fine. I could deal with not picking my car and earning free rental days on a faster schedule if I had to.
Boy was I in for a surprise. So far since going back to Avis in June I've had one car that had fewer than 25,000 miles on it. Granted it was a free upgrade to a SUV with four miles on it when I got in it, but still, that was one car out of six. The rest have been dirty inside, two have had large dents, and one was missing the passenger side sun visor. Then on Monday of this week I arrive at HSV, get the keys to my car at the counter (no true Preferred service at HSV) and go out to the garage. Again, the seats have visible stains on them, the cup holder has had coffee spilled in it that wasn't really cleaned up, and the dashboard is dusty. I drive off, get on the interstate and head into town. After exiting the interstate, I glance down and notice the gas gauge -- the tank is less than half full. I was too tired to turn around and go back to the airport, so I drove the last mile to the hotel, checked in, then called the HSV Avis number. At first they don't believe me, then they want me to drive the car 10 miles back to the airport to prove to them it wasn't full of gas. I refused. After a few more minutes on the phone I decided it wasn't worth it and to just let it go. I was tired and not in the mood to argue with someone who was refusing to believe me on this or do anything about it. So tonight I filled the tank so it's ready to go in the morning when I return the car. The low fuel light came on while driving to the gas station and it cost me about $29 to fill up the car. I really only used about half of the gas I put in the car. Granted, we're only talking about $15 here, and it will go on an expense report. But it's the principle of the thing! Why should I, or my client, have to pay extra money because Avis screwed up? Why should I have to waste 45 minutes-1 hour to drive back to the airport, park, get someone from Avis to come out and verify that the car's tank wasn't full when I drove it off the lot, and then argue with them about how to fix the situation? That time is worth a lot more than $15 to me.\
All of my coworkers who I've talked to about this have had similar issues. One had a car with a major dent all the way across the room; it looked as if a tree had fallen on the car. That car also had a cracked windshield. Another group of three coworkers was faced with an Avis agent at DEN who tried to downgrade them to a smaller car recently and still charge the quoted rate for the larger car they weren't getting.
This is not the Avis I rented from a couple of times a month for almost four years in the recent past. This is more like renting from one of the El Cheapo rental car brands. I might expect this kind of stuff from Budget or Dollar or Enterprise, but with the rates I'm being charged this is ridiculous.