Never Hand Out an Empty Loyalty Card: What a Car Wash Study Teaches Every Local Business

Picture a guest at your counter. You hand them a blank stamp card: eight empty circles, zero progress. It feels fair, since they haven't bought anything yet. But a real field experiment suggests a blank card is the weakest way to start.

Researchers call the alternative the endowed progress effect: give people a head start on the same amount of work, and more of them finish.

The car wash study (Nunes & Drèze, 2006)

Joseph C. Nunes and Xavier Drèze ran a field experiment at a professional car wash in a major US metro area and published it in the Journal of Consumer Research. On two Saturdays in April 2004, the car wash randomly handed out 300 loyalty cards, 150 of each kind:

• Card A needed eight washes for a free wash and started empty (0 of 8).
• Card B needed ten washes, but came with two stamps already on it (2 of 10). Customers were told the free stamps were part of a special promotion that day.

Both groups needed exactly eight more paid washes for the same reward. The only difference was whether the card looked already started.

What happened

• 19% of the empty cards were redeemed.
• 34% of the head-start cards were redeemed. That is almost twice as many.
• Among the cards that were redeemed, head-start customers took 2.9 fewer days between visits on average, and the gap between visits shrank as they got closer to the reward.

As the authors put it, the difference "occurred even though the absolute distance from the goal did not change." Same work left. Same reward. Different starting line.

Source: Nunes, J. C., & Drèze, X. (2006). The Endowed Progress Effect: How Artificial Advancement Increases Effort. Journal of Consumer Research, 32(4), 504–512. doi.org/10.1086/500480

Why a blank card feels harder

The authors' explanation: a card with two stamps on it turns the program into something "undertaken and incomplete rather than not yet begun." A started task feels like something to finish. An empty one feels like something you could skip.

In a follow-up survey of 240 shoppers at a liquor store (a hypothetical program, not a field test), the reason behind the free progress mattered. When progress was counted in purchases, a head start with no reason didn't move opinions much; giving a reason, even an arbitrary one like "because you are here today", made shoppers rate the program higher.

The owner rule: never start at zero

1. Give the head start on day one. One or two stamps when the guest joins.
2. Say why. "Welcome gift: your first two stamps are on us." A simple reason makes the gift feel natural.
3. Keep the real work honest. The power comes from reframing the same visits as already underway, not from quietly making the card longer.
4. Make progress visible. A guest who can see how close they are has a reason to come back.

This works for a restaurant, a café, a barbershop, a hotel (one stamp per stay) or any shop that lives on repeat visits. One caveat: this is one study at one car wash. It is a strong, cheap test to run, not a guarantee.

Paper card or Wallet card: same rule

Whether your card is printed or lives in Apple Wallet or Google Wallet, the psychology is the same: don't hand out empty progress.

In Westify's loyalty card, new members get welcome stamps by default (two, and the owner can lower it to one or none), and the card in the guest's Wallet shows how many stamps are left to the next reward. Owners can also add a smaller reward along the way to the main one. On iPhone, Apple Wallet can suggest the card on the lock screen when the guest is near the business; guests can turn that off in their phone's settings. Guests can delete their card and their data at any time from their card link.

How Wallet cards work: westify.app/blog/loyalty-card-apple-wallet-google-wallet
Stamp card vs points: westify.app/blog/stamp-card-vs-points-loyalty-program

What this is not

• It is not a review incentive. Never tie stamps or rewards to leaving a Google review.
• It is not a ranking trick. This post says nothing about Google Maps position.
• It is not a promise that every guest will finish. The study measured redemption in one field test; your results will vary.

Bottom line

An empty card asks a guest to begin. A card with two stamps on it asks them to continue. At the car wash, that was the difference between 19% and 34%, with the same eight washes to go.

Never start a guest at zero.

Westify loyalty card: westify.app/loyalty-card

Related: westify.app/blog/how-to-start-restaurant-loyalty-program and westify.app/blog/restaurant-loyalty-program-reward-ideas