Grime on back of car?

Grime on back of car?

I have a pearl Model S. I've noticed that on the rear end of the car there is a collection of a black, sooty like residue. It looks a lot like the bumper of a car that burns oil. I know that's not possible. I called OE and they told me they "think" it's probably dirt from the rear tires because they're wider than the wheel wells and dirt would be kicked up behind. There is certainly dirt on the trailing edge of the wheel well, but the center rear? I'm not sure I buy it. It wipes right off, but if you wash the car on Sunday and on Monday it looks like you're burning oil, I'm not sure what to do. Anyone else notice anything like this? On a silver car it wouldn't be noticible, but you can sure see it on the white.

Carefree | 5 March 2013

We have the same issue with our silver P85. It's amazing how much dirt collects at the rear of the car. There's an older threat discussing the same issue - use to find it.

rwang | 5 March 2013

+1. I thought it was the spoiler creating that much collection of dirt on the back, but it's a PITA!

mcptwo | 5 March 2013

I have noticed the same fine black soot on my Silver Model S. It only takes a few days to collect after washing. I thought it was the polluted air in San Jose, and that it was picking up the exhaust particles from the ICE cars. There must be a vacuum formed along the rear of the car that allows dirt to collect.

Velo1 | 5 March 2013

It would be great is TM would come out with matching color mud guards as an accessory. If done right, they would look like part of the car. Granted they'd affect aerodynamics, but I'd much rather prefer having a clean look much longer than a few days. For my use, the aero part is not important.

hfcolvin | 5 March 2013

The two Priuses I've owned have done the same thing on the vertical section of glass below the spoiler (kind of stretch to call it that on a Prius) on the rear hatch. Collects within a couple of days of cleaning and rain only seems to make it worse. Must be an aerodynamic thing.

David Trushin | 5 March 2013

My Cadillac SRX does the same. Back window get filthy quickly. I think this is a phenomenon related to cars not to Teslas.

nickjhowe | 5 March 2013

It is a function of the aero flow. The cars are specifically designed to create a turbulent region at the back of the car that gives the car a virtual tear drop shape and helps smooth the rest of the airflow. Unfortunately a side effect is to deposit cr*p on the back of the car.

lolachampcar | 5 March 2013

The crap is getting their because Tesla has airflow there. Nick is right. If the Cd sucked (punn intended) the back of the car would be clean.

Dirty butt please.... I like my Cd.

rterry | 5 March 2013

Notice the same grime after my first 10 mile drive in my silver MS. I waxed it before driving it and thought the grime gathered there because I didn't remove all the wax. I guess I did remove all the wax. Very interesting that this happens...I'll accept if it is helpful to the aerodynamics.

olanmills | 5 March 2013

This happened on my old car too, and wet roads make it worse. Yeah, crap collects on the back of the car and doesn't get blown away or rinsed away while driving.

DennisM | 5 March 2013

Yes, I've taken to dusting the rear end of my Pearl S every other day. Figured it was the aerodynamics - thanks to you all for confirming.

Robert22 | 5 March 2013

The dirt seems to wash off in the rain at about 115mph ;)

hnashif | 6 March 2013

I have a gray car. I only noticed it on the side of the backside of the back wheel wells. It is very powdery can be swiped off with a finger. | 6 March 2013

I haven't noticed it at all - likely because the car is Grey, and I've had it washed a few extra times than normal. I wonder which color hides it best?

lov2krz | 6 March 2013

It's dirt folks, every car on the road has it. It washes off easily.

Not to worry you can always repaint your car to a dark color (Green, Brown, Black, Blue) and it won't show. So if its dirty but you can't see it will it make a noise in the forest?

Brian H | 6 March 2013

depends entirely on the color of your local grime.

Pungoteague_Dave | 6 March 2013

Darker cars actually show more dirt than lighter cars, and it is true that due to its unique airflow, the Model S accumulates a lot of grime on the back end compared to any other car we have owned. We keep aerospace wipes in the rear footwell to wipe down the bumper before leaning in. We find it necessary to wash our Model S about twice as often as our other cars due to this "feature."

Some car manufacturers intentionally create airflow to avoid this syndrome - the reverse spoilers that catch air on the back of many minivan roofs are there to direct cleaning air down the aft end. This reduces mileage, so we don't want that on our cars - anything that would direct airflow to reduce the rear end dirt would also reduce range.

David Trushin | 6 March 2013

Pd evidently cadillac didn't do that with my srx.

drp | 6 March 2013

Definitely noticed this on my P85 gray. I thought it was just magnetic static from being wrapped during delivery but after washing the car it came back pretty readily. It doesn't bother me because I presume that it is related to the sweet aerodynamics which lead to the very low drag coefficient.

DonS | 7 March 2013

Pretty much all cars do this to varying degrees, with vertical back ends being most obvious because rain never washes off any of the deposit. I also understand there is also some triboelectric charging from the airflow over the vehicle (i.e. static electricity) causing grime particles to be attracted to the vehicle.

rmbod | 7 March 2013

So thankful to read this thread. I was feeling like i made a mistake picking mid-night blue for this very reason. thought the colored showed the dirt better.

+1 lola

cpetrush | 7 March 2013

I do notice it alot on my blue but the layer of yellow pollen hours after washing is even more annoying.

JZ13 | 7 March 2013

I looked for it on my Pearl white and could not find a part of the rear bumper that had collected more dirt than any other location.

Tomas | 7 March 2013

The services guys in LA told me that a Model S owner who is an engineer told them the reason that the back of the car collects dirt is because the motor creates "static electricity in the rear, effectively making it a dirt magnet. Sounds like a reasonable theory. Kind of like how static electricity makes a ballon stick to a wall (damn, I haven't done that in years. Maybe its time to roll that trick out for the kids!) They are experimenting with putting one of those straps that hang from the bottom of the car to the ground (like those you see busses and trucks) on the car to see if grounding the car that will discharge the static electricity. They are putting one in my car tomorrow. I think it will likely look way too ghetto, but they asked to test it out and i so agreed.

olanmills | 7 March 2013

@Tomas, while that could be the case, this is also an issue in wet weather with dirty water sort of depositing dirt in the back, and so I don't think it's just an issue with static electricity.

As I mentioned, my old ICE car had this issue too.

Brian H | 7 March 2013

Mist also responds to static. Dirty mist, even better.

torst1 | 8 March 2013

Pls let us know if the static discharge trick helps.

David Trushin | 8 March 2013

My ICE used to collect goose droppings on the roof. So far nothing on the S. Maybe they like the fact that there are no emissions. Now if only there was an electric goose....

torst1 | 10 March 2013

To all of you that already have a Tesla S and are fed up by the mud, grime and dirt on the rear of the car. You might wanna test out Ultra Ever Dry that uses nano tech to "air-cussion" products.

Check this out:

petero | 10 March 2013

Perhaps the flat (sealed) under body contributes to the rear dirt.

hwye81k | 10 March 2013

torst1, have you tried it? If so where did you buy it?

Oliver in Seattle | 10 March 2013

The dirt isn't as apparent on the gray, and the cool thing is that my rear plate is now the same color as the car.

torst1 | 11 March 2013


No I have not tested yet myself as the order is yet in shipping.
You can get from and I am sure other places as well.

For me I can always use it to waterproof my hiking boots if it does not work magic on cars like it does in this vid:

Hills | 11 March 2013

Yes, the back of the car seems to be made of dust magnets. Also, after driving in the rain, the back of the car is far dirtier than the rest of the car.