W210 OM606 Turbo MPG log for road trip
 

There's been a good bit of discussion and variance in the reported MPG's for the W210 cars with the OM606. I'm planning on doing a road trip to Philly this weekend so I thought I'd fully document it and share my real time MPG figures.

The plan:

I will only fill up when the tank is mostly empty, say down to about 1/4. Since the tank fill is the least accurate part of the test, I thought I'd try the following procedure to increase the accuracy of the fill.

Set the pump handle on "fast" fill for the first 13 gallons.
Set the handle on "slow fill" until it automatically shuts off. (Minimize foaming)
Manually dispense one last gallon (or whatever I can to start with) and do the same exact thing for subsequent fill ups

Of course this all depends on how the pump is set as far as delivery pressure and speed so I will have to monitor it and attempt to ensure accuracy.

On the trip up, I will be driving country roads through small towns so there will be a fair amount of slower driving and some stop and go. The trip back will be all interstate. In both cases, I will drive reasonably, accelerate smoothly but not overly rapidly but I will not "hypermile" it.

Along the way, I will take and post pictures of my gauges when I make stops where I have to shut the car off. During this time, I will suspend my running time clock in order to maintain an accurate average speed calculation.

My results will be posted with MPG's and average speeds. If anyone has a suggestion for improving accuracy, speak now so I can plan on implementing the ideas.

Stay tuned.

Check your tire pressure. Include what you set it at in the trip data.

How many miles is the planned route ?

Do we get a prize for guessing closest to the actual MPG (without overbiding) ?

Good idea, I'll do that.

The trip will be about 1000 miles. And for a prize you get the respect and admiration of your forum mates... :)

Thanks, Evan. We're rooting for you (and your car)!

I would be interested in the full trip start to fill back home mpg not just the segments.

Ok, I'll add that as well.

Why not keep it simple and just fill it to the brim each time?

Agree with this strategy. It's what I do. Sometimes the nozzle clicks off with the tank almost full and other times there is lots of foam and it takes patience to let the foam recede and bring the level up to the same reference point. Pick your reference level and fill to that every time.

I can give it a try but the foam usually keeps me from filling it properly. When I fill up for the trip, I'll try slow filling and then squeak it in until it reaches a set point in the fill pipe.

I'm trying to make the fills exactly repeatable.

The problem will be the types of stations and their pumps. I've noticed a wide variance on the flow I can regulate from the different diesel stations pumps... Some I can feather down to a trickle easily, and some are nearly all on or off with little control...

Try to use trucker stations for the most consistent fuel and control.

Fill it at your home station at the beginning and end of the trip. The total gallons for the trip should be fairly accurate even if the gallons for one leg of the trip may be slightly inaccurate.

Let us know when you return and give us a chance to guess-your-weight before you give it up.

Well, it was a long challenging day. I got started around 9AM and ended at 7:30PM covering 454+ miles of country roads, stop and go, 20 MPH small towns and about 2 hours of free moving interstate.

About half way through the trip, I was on a rural highway when I met a truck hauling junk. We were both running around 55 and when I got about 50 yards away something that looked like a piece of wood fell off the truck and came cart wheeling towards me. There was nowhere to swerve so I just hit the brakes and tried to straddle it. About a millisecond after I saw it hit the road and flip a couple times, I heard a "clang" and realized it wasn't wood, it was a steel plate about 18" long and 6" wide and it was still flipping end over end towards the car. All I could do at this time was try to stop and watch out to duck if it flipped up and came through the windshield.

Lukily it hit the lower front of the car on the air dam at the left hand fog light. I heard a "thunk" "bong" as if it had bounced up and hit the rear spring. Again, no where to stop so I kept an eye on the gauges to make sure nothing was punctured.

As soon as I could, I stopped to check it out but couldn't really see anything. Will check more tomorrow in the daylight.

Anyway, back to the matter at hand:

This morning I started with the tank full to the rim, tire pressure at 30 and 34 front and rear. I didn't use the air conditioning and my speed averaged out to be around 45MPH.

Shall I post a picture of my gauges when I stopped or just let the guessing begin?

Evan, do you use 30/34 tire pressure because of full load or is that your normal pressure when driving alone?

The sticker says 28/34 but the car plows so badly under hard cornering that I put a little more in it. Really, to get the most performance out of it the fronts need about 40 PSI but then the rear end starts wanting to come around.

Holy cow, good thing you're still around! That sounds very frightening.