I have a really good problem! Great MPG
 

My 300D's fuel economy is so good that I double checked everything to remove any doubt! Now this is all highway MPG so here goes.:D
1. I had replaced my speedo with a rebuilt one since mine had recently quit racking up miles. I had my next door neighbor, an Arizona Police officer check my speed with a radar gun against my moving vehicle to see how fast I was going. OK. Several times the radar gun and my speedo agreed withing a 1 to 1.5 MPH variable at 45 MPH. Close enough.

2. I'm running B99 and have since I got the car with those rare exceptions when I had to get a little dino! Maybe 4 times in the last year and never more than 2/3rds tankful. My idle went up gby 150 RPM just using it once it made it through the system in a couple hundred miles. Now my oil changes look super cleaner and my emissions test was 2% opacity read and up to 20% allowed.

3. My only engine maintenance change was to advance the injection timing by 2* to make up for Biodiesel having a slightly lower BTU. I maintain my vehicles well, never let maintenance ever take a back seat to something else. I even check my bolt torque on my engine accessories regularly, Power Steering, AC pump...etc.

4. I went on a Sunday drive with a friend of mine around Arizona and we wound up at Wickieup on highway 93 and had lunch there.
I refilled Mr Benz at Wickieup and drove 211 miles back home. South on 93, the Barry Goldwater/Joshua forest scenic parkway to Highway 74 at Wickenburg.
Turned left on 74 and took it to southbound 17, The Pearl Harbor memorial highway, then southbound 17 to Eastbound 101, The Agua Fria freeway to Eastbound 202, the Red Mountain freeway to it's end at power Rd. South on power Rd. to University and East on University to Idaho. South on Idaho to the Wild west highway which took me to my 1958 Ranch house in Superstition Vista!:D

Now for those looking on a map and you can see how far I went. My problem? This is 211.6 miles since resetting the trip odometer in Wickieup and I watched the mileage markers while driving, very slight discrepancy, OK?

GALLONS OF FUEL USED FOR THE RETURN TRIP........5.5 GALLONS!:eek:

How is this possible? Is Biodiesel such a superior lubricating fuel that is can really help with good fuel economy like this????

This comes out to be 38.472 MPG! WTF?!:confused: And man, we were going about 70 nonstop! :D Can anyone think of something I over looked? The first thing I doubted was my speedo, but I make this trip in a Freightliner every week for the last year from Andy Devine in Kingman, so this mileage is about right!

My glow plugs are clean when I took them out to look at them and it even look like most of the carbon has been eaten away by being consumed somehow. My exhaust is the cleanest I've ever seen is a diesel. I filled a VP racing fuel can with exactly 5 gallons from my private fuel tank (470 gallons) and poured that in Mr Benz. I filled another and it was full at 5.56 gallons according to the marking on the outside of the can! I poured the remainder into ANOTHER jug and got just a little under 4.5 gallons back!

Now I double checked myself because everyone says on this board that these cars just don't get this kind of mileage. OK. No one ever made this kind of test with Biodiesel before to the best of my knowledge!

That Was All Downhill !!!!!!
Lol

That would have been a good explanation, but realistically, this was fairly flat once we got past Burro Canyon! :D I didn't run the AC since it was only 76* and it felt good to have the sunroof open.:cool:

I'm thinking you'd better get that car listed on ebay, now that it can compete with all of the other w123's that get over 30mpg ;)

Have you changed your stock fuel lines to the the Viton (?) rubber? It's my understanding that biodiesel will cause normal rubber to break down.

John

That's correct, organic rubber does not like biodiesel! I did switch my larger fuel lines to Fuel Injectiion hose. It's my understanding that this is Viton Rubber. The little hoses that go from injector to injector and back to the fuel return line I cant yet find in Viton, so I jst keep several feet in the trunk and replace it periodically when it start looking like it's seen better days!:D

Perhaps your car is burning its crankcase oil as fuel.

Check oil level NOW.:D

No, it didn't burn a drop! I've never really had that problem with this car. It was right on full when we left and it was still there when we got back!:D This is weird, but at todays fuel prices, I'm not complaining!:D:D:cool:

I heard of a group of coworkers that got tired of one of them bragging about the mileage his car got... so they started adding fuel to his tank each week... more each week... they really had him up to a LOT of perceived Miles per gallon before they told him the truth...
.... Anyone else have access to your fuel cap ? LOL

A forum member sells those. His name is JaDavis. Here is his website. He has O-rings too.


http://www.fryerpower.com/store/page11.html.

[QUOTE=Knightrider966;1812404]My 300D's fuel economy is so good that I double checked everything to remove any doubt! Now this is all highway MPG so here goes.:D





How is this possible? Is Biodiesel such a superior lubricating fuel that is can really help with good fuel economy like this????

No it is not that super a lubricant. I consistently saw lower FE when I was burning B99. You must be getting some really special biodiesel.:D

You probably did not get an accurate read on the gallons used.

There is no way it was that good.

Sorry.

Tom W

I agree with Tom... so you should keep checking to see if there is a glitch in the data accumulation...
How many miles does the map show that to be... as compared to using your speedo to measure the distance... ?

Get back with us after a few tankfuls.