titanium

After driving a couple of days on our salty roads the car looks like this on the rear end. Not a pretty sight

The rest of the car looks really fine. Nothing to be ashamed about.
The thing is, I really hate a dirty car so much time is spent washing, washing and again washing . . .


If you look at the picture below you can see that there is a sharp border between the rear end and
the side of the car. The airflow seems to produce a whirl over the rear end and that sucks up all
the dirt from underneath the car. Not so good !
I?ve had several estates and none of them have had theese severe problems with "blackened out" rear end



So what can be done ?
Do I have to drive like this ? Disguised


Any thoughts ?

PSB

i dont think there is much you can do about this .. its the physics of the car .. when u drive a low pressure area is built behind the car eddie circles are formed in the air .. this will pick up any dirt behind and since there is snow there are more things in the air to pick up .. i guess a hatchback will go thru this problem more than a salon because its less airo-dynamic

titanium

You are right about that.
Is there any difference between cars with or without the M-package ? Is the airflow better on the non M?s ?

Rudy

I think you're seeing the result of good aerodynamics, not poor aerodynamics. You will always see more of this type of dirt on a wagon (or SUV) since the rear window is moved to the back. That's why there's always a rear wiper on these types of cars.

Not much you can do about it except wash it down a bit.

I am reminded, however, of the rear light style that Mercedes used back in the 80's -- they had grooves in them that were supposed to help keep them cleaner. Sometimes, they'll put a little flared edge/lip on the side of the rear light to help break up the airflow in an attempt to keep the lights clean. Does the Touring have a little lip at the rear?

titanium

It has a little lip.

And you can se some difference in how the light is dirtied.

las77

My car is just as dirty (non M package).

I think also that the wide tyres kick-up the dirt too. My wife's E-class estate is not as dirty at the back. Her tyres are not as wide.

Wonder what the back would look like with no mud flaps?

obiwan

Our T is the same way.
Likely because of this, the volvo wagons have taillights set on the pillars and higher.
I think the Honda CRV amongst the SUV's also has tail lights set higher.

For snow, LED lights will not melt snow that gets stuck to the tail lights as regular lights will or for that matter, rear fog lights

E60Sim

Ohh, now I'm glad I moved from Stockholm back to Denmark 3 years ago.. All that salt + gravel on the roads, makes the cars look like a nightmare! Dry roads here i Denmark, and the E60 is like a mirror right now

We haven't got any snow at all this winter!

tachyon

I think this is correct ... if I remember my fluid dynamics from college (no, not the beer kind - although, that's why I don't recall too much ).

If the air flow over the car is not efficient - i.e.; turbulent - then the dirt particles would fly further away from the car in the downstream wake. On the other hand, smooth airflow over the car creates a tight slipstream behind it, and hence, the low pressure area where all the particles gather.

phelix

I should have posted a picture of my car before I cleaned the lights and rear plate after driving from the UK to Switzerland. The standard yellow UK rear plate was completely black; it was not recognisable as having a yellow background. The BMW roundel was black. Just waiting fro things to thaw out long enough to wash the car.