I have been Avis Select Preffered for the last few years, but I feel like I don't get much for it. I am looking at recommendations for the best car rental program. I want to get free rentals and upgrades out of this.

I haven't found a better program than Hertz. I'm also PS and will never go back to Avis for my business rentals.

If you rent at least 10 times per year, you can earn "5 Star" status. That basically provides a 1 class upgrade if availble. In addition, you'll earn a free day coupon after every (I think) 15 rentals.

After 40 rentals in a calendar year, you can get to "Presidents Circle" status. That's when things start getting interesting.

As a PC, your guaranteed at least a 1 class upgrade. Often I've received several class upgrades. In Houston, I would rent a Midsize and very often (every week for 8+ weeks in a row) get a Infiniti G35. After adding the G35 to my profile, I also get it on weekends in LAX, ORD, and PHL.

Last fall, in Honolulu we reserved a full size and got a Caddilac Deville using a free day coupon. In IAD, reserved Full received a Lincoln Towncar ultimate, on a free weekend coupon.

I've never failed to receive at least a 1 class upgrade, and usually get a several class upgrade. Though sometimes they go too far and upgrade me into a gigantic boat, like the Grand Marquis that I don't like. Usually I can go in and ask for a downgrade to something more normal.

In addition, the selection of high end cars at some Hertz locations is really great. Jaguars (X-Type, S-Type, XJ8, XK8 convertible), Caddilac Escalade, Land Rover Discovery, Infiniti G35 FX35 Q45, Volvos, Lincoln, Audi A6, Hummer H2, plus usual cars like the Mazda 3/6, Toyota Solara Camry Avalon, Nissan Altima Maxima, Kia Amanti, Subaru Outback... etc.

I select Hertz ZE1 points instead of airline miles or hotel points (1pt / $1, 25% bonus for PC level members). For our vacation this fall we're getting a Jaguar S-Type, XK8 or Lincoln Navigator for a week using 5,000 points. I think that's a great deal. We would never pay the $800 weekly rate for one of these cars.

I'm willing to drive an occasional Taurus or Grand Marquis to get a fabulous car using points for our vacations.

I believe National may give you free rental days much faster than Hertz, but no other program has been as consistently good for me.

I am a relatively infrequent renter from Avis, with only about 5-6 rentals per year. I have a simple Preferred status. In the last year I have received coupons from them for a free 2-day rental and a free 1-day rental. Maybe they have a special award program for California rentals.

I got AVIS Preferred Select as a "comp" from a VISA Signature card. Although AVIS rentals often cost more than other companies for the intermediate size category I usually request, so far I have had very good luck with upgrades in several countries outside of the US. I haven't really evaluated the merits of these so-called upgrades over simply paying more in the first place, but the AVIS cars strike me as very well maintained.

Tummy is right. National gets you free rentals much faster, but the selection of cars is not nearly as good, especially at the higher end.
I was Hertz PC for a while and switched to national about 2 years ago to get the free days faster. Though some colleagues that I work and travel with pretty much had a G35 every week in CHS for a year. I was kind of jealous.

Depends what you are looking for. Nicer cars after more required rentals: Hertz. Accumulation of free rental days faster: National.
My 2 cents, anyway.

I've been PS for a number of years. Service is OK, I usually get an upgrade to something I don't want, but a polite request will usually get me anything within reason. I got a black 2005 mustang at BNA on Wednesday by asking. Although there seemed to be some kind of Corvette convention in Bowling Green, some people at my hotel were gawking at the car when I had it sitting in the lobby drive up area. I hate the Buicks and Impalas I usually get from AVIS, but lately they seem to be getting other makes. My company only has a contract with AVIS so I'm not at liberty to go elsewhere. I get Hertz when AVIS is unavailable, but I doubt I can get past 5 star. If I had a choice and could go with any rental company, I would choose Hertz if I could get the 40 rentals for the top level. My 100 rentals a year with AVIS doesn't get me much other than a lot of BA miles.

National Emerald allows automatic upgrade from a midsize to a full size via the Emerald Aisle program. Basically, as a member, you could reserve a midsize car and go to the rental locations and pick out any of the car that is in the Emerald Aisle. Most of the time, the cars in the Emerald Aisle are full size cars, and up to a basic SUV model.

Also, use the entertainment coupons for free weekend days, and you could save a bunch of money.

If you are able to get Avis Presidents Club, it certainly beats the Select membership hands down. You get multiple tier car upgrades among other things. In my experience, when renting an economy car at airport locations, I have been offered a car of my choice at the counter.

National's Emerald Club is the best rental car program on the market.

After 10 rentals in a calendar year, you get Executive status, which gives you access to the "Executive Selection" with guaranteed upgrades (pay the intermediate rate for a full-size or higher). After 25 rentals in a calendar year, you get Executive Elite status, which guarantees a car for you at any National location with 24-hour notice, even in sold-out situations, and for an extra fee your National car can be delivered to you at a general aviation airport within 50 miles of a National counter.

As Executive Elite, you earn free rentals three times faster than Hertz. Every five paid rentals gets you a free day valid at any location, with no capacity controls and no drop-off fees if you're renting one-way. I use all my free days for one-way rentals, where they can save hundreds of dollars. As Executive Elite, the free days even work for renting Luxury cars, such as the Cadillac DeVille (though this seems to be either an unpublished benefit or a glitch in National's system; normally the free days apply only to full size or Executive Selection vehicles).

Granted, National doesn't have a Prestige Collection like Hertz, but for the intermediate rate you can pick from a whole array of full-size cars or better in the Emerald Aisle or Executive Selection. Most airports put some premium vehicles, SUVs and minivans along with the full-size cars in the Executive Selection, and as long as the car is in that area you can rent it at the intermediate rate if you're Emerald Exec or Exec Elite. Even the standard Emerald Aisle usually has a diverse offering of vehicles. National's cars are mostly GM with a few Chrysler Corporation products thrown in. The Pontiac G6 (Emerald Aisle) and Buick LaCrosse (Exec Selection) are currently "exclusive" to National, and both have XM satellite radio and sunroof for no extra charge. Personally, I prefer the Chrysler vehicles such as the Sebring coupe and Jeep Grand Cherokee.

At locations with an Emerald Aisle/Exec Selection (most major US airports), the car rental experience couldn't be faster. Either walk or take the shuttle bus to the National lot, pick the car of your choice from the aisle, and drive to the exit booth with your driver's license and Emerald Club card. Within a couple of minutes, you'll be out of the rental facility with no need to stop at the counter.

I chose National over Hertz at first just because National was the only top-tier agency willing to take my business; I'm an under-25 frequent renter for both business and pleasure. But even once I turn 25 (or sue Hertz and Avis for age discrimination) I'll probably stick mostly with National because I enjoy the ease of choosing my own car from the lot, the generous free upgrades, and the low rates. Check on the National board here on FlyerTalk for some contract ID# that can provide some big savings. Most of the time, when I've checked Hertz rates for others, National comes out cheaper, especially for one-ways.