Going on a Long trip in July (as you probably already know)

I have no AC working in the car and the sunroof is going to be open most of the way. I was wondering would a ventshade visor for my sunroof improve the aerodynamics over an open sunroof?

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RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)
2002 ML500 'sport'

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FACEBOOK: PANZER450

You're splitting (h)airs on that one i should think.

When the sun roof is open, a small "spoiler" pops up anyway.....and I think there is very little drag with open sun roof, since the air stream over the car basically goes up and over....you do hear some turbulence, so there is some drag, which would be lowered by one of those visors, but I don't think you would see any real noticable effect on mileage. (those visors are nice for allowing you to use the sun roof in the rain). If you had a bike or luggage rack on top, that would be a different story....those spoilers they sell for these racks have a big effect in lowering drag...but put a couple of bikes up there, and I think there would be measureable effect on mileage.

If you want to absolutely maximize mileage, avoid fast acceleration, passing, etc., and most important keep highway speeds between 60 and 65.....I can get 30 mpg max like this. If I travel my usual speed of between 70 and 75, my mileage drops to 25.

good luck,

Mark

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1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)

I have a different method for mileage when I travel.

I've read several articles that claim the aerodynamics on cars has been at a point for several years where opening a window can create more drag than running the A/C. This is of course provided your A/C works, and it's efficient. The old York compressors maybe not.

Aero drag is the largest consumer of fuel on the highway, so keep it as clean as possible (aerodynamically speaking). Even antennas have gotten the attention of automakers in the last decade and side mirrors for their drag and effect on mileage (One good thing from CAFE).

Even a wax job can't hurt, at least you look good!

Weight matters, don't carry weight you don't need. If you open windows/roof, find out which ones create the least disturbance in the car, you can hear turbulance. I like to run the RF and LR open a crack for circulation, quiet and good turnover without significant turbulance, ... noise is energy.

Rolling resistance matters. Most of the time the harder the tire, the lower the rolling resistance. It will ride more harsh, but if you're traveling fairly smooth roads that is just a comfort thing. Really rough roads will burn more energy.

I have a forumula around here, on my other computer, I will post it if I find it, into which you can plug your Cd, frontal area, weight, etc. and see how much HP you need to maintain certain speeds. This formula makes it quite apparent that aero drag is the biggest consumer of power on the highway. Speed increases aero drag logrithmicallly, so a little more speed is a lot more drag/fuel.

The little things matter too, such as a smooth driving style, and lubrications. I believe that premium oils and lubricants are a significant factor in the efficient transfer of fuel/heat to rotating wheels, ... which oil/lubricants are best is a topic best left alone on automotive forums though.

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Gone to the dark side

- Jeff

I was making a road trip from MS to AZ in my 79 300SD when I got a severe oil leak (1qt/100miles) that only leaked above 60. When I drove an entire tank with the cruise on 60 I got 28mpg . Normally going 80-85 I get 23-24. In town I get 19-21.

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John Robbins
'05 E320 CDI - 240k
'87 300TD - 318k

reading through these posts, one thing I haven`t seen mentioned is the
wind. with a head wind it will decrease the milage, and a tail wind it will
increase our milage. also a cross wind has some effect.
so always make sure the wind us blowing up your uh um tail.
charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

run your tires at the highest PSI you can stand (up to the max rated on the tire sidewall), make sure your alignment is correct, mix 1 oz. each of silver Power Service Diesel Kleen summer formula and Marvel Mystery Oil per gallon of diesel fuel, make sure your brakes aren't dragging, keep the speed down, draft off large semis to reduce wind drag-am I sounding like a big-time tightwad yet???

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1982 300DT 190K (Diesel Purge + synthetic oil=smoothness at last!!!)
2004 Ford E-350 6.0 L PSD 227K
2006 Dodge Ram 3500 SRW HO Cummins 4X4 48RE 42K (brute force tow vehicle)
2005 Scion xB wife's rolling pop can
1993 GMC Sierra C3500 6.2 142K

Drive slow. 55 mph should do it, your mileage will be great!

I can't drive that slow, I get pissed off on a trip if I can't do at least 70. Screw a mpg or two I want to get their before I grow old and die.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

how about if we chop the top, shave the door handles, drip rail, side molding, antenna. add some ground affects and install a wing on the trunk. and have to have that coffee can muffler.

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

.
Hello Everyone

Don't drag race to the next red light.

Look ahead of you at the next traffic light.

If it is red, slow down.

I do not know how many times the people beside me floor it at a green light,
only to slam on the brakes at the next red light.

Then I slowly make it right back up to where they are stopped just in time for the light to turn green.

It gets kinda funny seeing the same person trying to pass me over and over and over.

The people behind you sometimes get pissed and tailgate you, and sometimes they figure out what is going on,
and that they are getting thru traffic just as fast as everyone else,
without all the stopping and starting.

Thank You
Still not right after all these pills !!
RichC

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When the power of love overcomes the love of power the world will know peace.
Jimi Hendrix

I just ganked a vent visor from my 200D and was pleasantly suprised at the amount of air circulation I got. Probably be nice when its lightly raining to.

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http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42