Turn on creep and maybe put in neutral.
I looked in the manual (because I wanted to take my car to a car wash that does hand wash but still puts it on one of those rail things to pull it through", and while you can put it in neutral, the manual says that if there is no occupant in the drivers seat it will switch to park.
====================
Neutral
Push the lever up or down to the first position
and hold it there for more than 1 second to
shift into Neutral. Neutral allows Model 3 to
roll freely when you are not pressing the brake
pedal.
If Model 3 is in Park and you use the
touchscreen to release the parking brake
(Controls > Safety & Security), Model 3 shifts
into Neutral (see Parking Brake on page 55).
Model 3 automatically shifts into Park when
you exit. To leave Model 3 in Neutral, use the
touchscreen to engage Transport Mode (see
Instructions for Transporters on page 161).
===================
But, if you look at the instructions for transporters on page 161 as it directs, it tells you that the car should never be "towed with wheels on the ground, even for short distances". I would consider car wash rails to be "towing on the ground for short distances", but maybe others see differently? In any case, I believe at a car wash, one "could" put it in transport mode so that it was in neutral without someone needing to be in the car.
======================
Never tow Model 3 with the tires contacting
the ground, even for short distances. Doing so
can cause significant damage. In addition,
before pulling Model 3 onto a flatbed truck,
you must use the touchscreen to enable
Transport Mode. Transport Mode keeps Model
3 in Neutral, allowing the tires to turn freely.
Transport Mode also prevents damage that
would be caused when the tires turn as you
pull Model 3 onto a flatbed truck.
Do not
attempt to use Transport Mode to tow Model 3
with the tires on the ground. Transport Mode
can prevent damage only when used for a
limited time and speed, and for a very short
distance, such as when you pull Model 3 onto
a flatbed truck. If you are unable to activate
Transport Mode, you must use self-loading
dollies or tire skates to prevent the tires from
turning as you pull Model 3 onto a flatbed
truck.
Warning: TOWING MODEL 3 WITH THE
TIRES CONTACTING THE GROUND CAN
CAUSE OVERHEATING AND DAMAGE TO
THE REAR MOTOR.
Warning: To prevent damage and
overheating of the rear motor when
rolling or winching Model 3 onto a flatbed
truck, you must either enable Transport
Mode or use self-loading dollies or tire
skates. Do not allow the tires to turn
without Transport Mode enabled.
Note: Tesla is not responsible for any damage
caused by transporting Model 3, including
personal or property damage caused by using
self-loading dollies or tire skates.
========================
Speaking of Car washes... tesla has a chapter in the manual about washing the car. I dont remember seeing such in the car manual for the BMWs I have had, but maybe it was there. Interesting all the verbiage they have about car washes....
=========================
Cleaning the Exterior
To prevent damage to the paint, immediately
remove corrosive substances (bird droppings,
tree resin, dead insects, tar spots, road salt,
industrial fallout, etc.). Do not wait until Model
3 is due for a complete wash. If necessary, use
denatured alcohol to remove tar spots and
stubborn grease stains, then immediately
wash the area with water and a mild, nondetergent
soap to remove the alcohol.
Follow these steps when washing the exterior
of Model 3:
1. Rinse Thoroughly
Before washing, flush grime and grit from
the bodywork using a hose. Flush away
accumulations of mud in areas where
debris easily collects (such as wheel
arches and panel seams). If salt has been
used on the highways (such as during
winter months), thoroughly rinse all traces
of road salt from the underside of the
vehicle.
2. Hand Wash
Hand wash Model 3 using a clean soft
cloth and cold or lukewarm water
containing a mild, high-quality car
shampoo.
3. Rinse with Clean Water
After washing, rinse with clean water to
prevent soap from drying on the surfaces.
4. Dry Thoroughly and Clean Exterior Glass
After washing and rinsing, dry thoroughly
with a chamois.
Clean windows and mirrors using an
automotive glass cleaner. Do not scrape,
or use any abrasive cleaning fluid on glass
or mirrored surfaces.
Cautions for Exterior Cleaning
Caution: Do not use windshield treatment
fluids. Doing so can interfere with wiper
friction and cause a chattering sound.
Caution: Do not use hot water or
detergents.
Caution: Do not wash in direct sunlight.
Caution: If using a pressure washer,
maintain a distance of at least 12" (30 cm)
between the nozzle and the surface of
Model 3. Keep the nozzle moving and do
not concentrate the water jet on any one
area.
Caution: Do not aim water hoses directly
at window, door or hood seals, or through
wheel apertures onto brake components.
Caution: Avoid using tight-napped or
rough cloths, such as washing mitts.
Caution: If washing in an automatic car
wash, use Touchless car washes only.
These car washes have no parts (brushes,
etc.) that touch the surfaces of Model 3.
Using any other type of car wash could
cause damage that is not covered by the
warranty.
Caution: Ensure the wipers are off before
washing Model 3 to avoid the risk of
damaging the wipers.
Caution: Do not use chemical based
wheel cleaners. These can damage the
finish on the wheels.
Caution: Avoid using a high pressure
power washer on the camera(s) or
parking sensors (if equipped) and do not
clean a sensor or camera lens with a
sharp or abrasive object that can scratch
or damage its surface.
Warning: Never spray liquid at a high
velocity (for example, if using a pressure
washer) towards the charge port while
Model 3 is charging. Failure to follow
these instructions can result in serious
injury or damage to the vehicle, charging
equipment, or property.