I use at least one in all of my vehicles, trailers and boats, along with a third party tracker in the more valuable. AirTags are a quick way to get an update on where your vehicle is. They use the cellular network relayed from an iPhone or Apple product. Given the popularity of Apple products, none of mine have failed to update, even in the vehicles I have in storage, since there is always someone on the property walking around. About 25-30 feet is the pickup distance. You can't beat them for $25/each.
Be aware that your Apple bearing passengers may receive a notice on their iPhones that lets them know there is an AirTag traveling with them, so don't plan on keeping it a secret if you transport friends.
If they think I'm being paranoid tracking my vehicles, ask them if they would have liked help locating their vehicle if they forgot where they parked at the shopping center, or would like to know if their mechanic is taking joy rides in their cars after repair. That usually works.
P.S. Battery life is usually about 2 years.