Reason for this is two hours before you are scheduled to show up, your reservation is opened into a contract, assigned a vehicle and preprinted. When this happens, your reservation is no longer listed in the "pending reservations" list in the computer system (an agent's initial reaction to this would be thinking that you booked with another company, booked the wrong date, or are under a different name). Ideally, all agents should be familiar with the day's Bluechip customers and recognize your name, but at a larger location with many agents and hundreds of reservations, this isn't likely (hence the dedicated BC counter at these locations--if you walk up there, it's obvious).

If the agent doesn't realize you're BC, he/she can run a manual search by name and see that the reservation has been opened and that you're BC, but it takes an extra 30 seconds to do so--which defeats the purpose of BC (which is to speed you on your way in 60 seconds or less). Best to let them know up front just to make life easier (and no, it's not necessary to show your BC card--that's just a memento to make you feel special).

The whole point of opening the RA, printing it and preauthorizing your card is so that the agent doesn't have to dig up your info in the computer--it's all done in advance so all you have to do is sign and go. The only time the agent should have to access the computer is if you want to change an option (such as adding gas or coverage or upgrading) or use a different credit card than is in your profile or the credit card declines the initial authorization. If your arrival time is significantly different than your reservation time, the agent should go back into the computer after you leave and update it so your rental charges will be correctly calculated, but it might not hurt to have the agent physically write the time on the Thrifty copy (which actually is policy) and maybe even write it and initial it on your copy just in case (it might help you with disputes with overtime charges if they don't change it in the computer).

Some other BC benefits are guaranteed satisfaction (a free day if you're not), (mostly) guaranteed availability if the location's oversold (not a pretty day--no agent wants to be there in that nasty event--if they do, though, a good location will at least have made arrangements with another company and will reimburse any difference in rate), the 60-seconds-or less promise, optional Bluechip rewards (one free day for every 16 rental days if you opt for BC rewards over airline miles), a possible better response from customer service if you have any disputes and access to a special Bluechip customer service number, hassle-free rentals with no sales pushes (since you've already indicated your rental preferences), the dedicated counter and/or getting to cut in line, and holding your reservation until closing or midnight instead of the normal two-hour (supposedly now six hours at airport locations) no-show policy. The program is free, so it doesn't make sense not to sign up for it even if you only plan on renting with Thrifty rarely or occasionally.

The downsides of BC are possibly losing out on free upgrades if they're sold out of your reserved class (depending on the agent's mood, they might stick the last midsize on your rental and give all the other customers fullsizes and luxuries, or they might decide to be nice to the Bluechips and give them the free upgrades first...especially if you opt to take coverage or gas in your profile, hint hint...) and the preauthorization on your card (which means potentially hundreds of dollars of your credit limit is being tied up for 5-30 days even if you don't show up, so use a higher-limit or lesser-used card). However, with the number of people complaining about gas mileage these days, agents are hesitant to give BC members free upgrades in advance, as they don't want to get yelled at by an unhappy person...

Note that Dollar Express is an almost exact duplicate of the Thrifty Bluechip program (even down to the free day for every 16 days rewards, although they're not combinable with Bluechip). Note that Dollar Express does not have the same free day satisfaction guarantee, though.

I know I'm slightly OT, but I figured I'd give an overview of the program for people who may not be familiar with it...