Automatic washes are fast and cheap. They are also the single most common cause of swirl marks in modern clear coats.
There is a place for the drive-through wash. But it is worth understanding exactly what you are trading away for the convenience.
What the brushes are carrying
In a tunnel wash, the same cloth or brush strips touch every vehicle that goes through. Whatever came off the pickup ahead of you — sand, grit, brake dust, road salt — is still in those strips when they reach your paint. Dragged across a clear coat under pressure, that grit cuts thousands of fine scratches.
Those scratches are what people call swirl marks. In direct sunlight they show as a hazy spiderweb pattern, and they are the main reason a three-year-old car can look considerably duller than its age.
Touchless is better, with a catch
Touchless washes avoid physical contact, which removes the swirl-mark risk. To compensate for not scrubbing, they use much stronger chemicals — typically high-pH detergents that strip wax and sealant along with the dirt. Used occasionally that is fine. Used weekly, you are removing your protection every time.
What hand washing does differently
The two-bucket method exists specifically to stop grit going back onto the paint: one bucket holds clean soap, the other rinses the mitt, and a grit guard traps what falls off. Work panel by panel with clean media and the paint is never asked to tolerate abrasive contact.
Drying matters just as much. Plush microfiber towels lift water without dragging, where a squeegee or a public air blower pushes residual grit straight back across the finish.
The part a tunnel cannot do at all
No automatic wash touches your interior, and interiors are where most of a vehicle's value quietly disappears. Ground-in carpet dirt, stained seats and lingering odours affect resale far more than a clean exterior does — and none of it is addressed by any tunnel wash at any price.
The honest recommendation
If you need salt off the paint quickly in mid-winter, a touchless wash is a reasonable stopgap. For everything else, hand washing protects the finish, and periodic interior work protects the value. Mobile detailing adds the practical advantage that none of it costs you a trip.