Use this very accurate fuel calculator from the EPA and it will show you how much you will save going with diesel.

https://mbworld.org/forums/gl-class-x164/229097-fuel-economy-calculator.html

Amazing that our tax dollars can produce something that's actually useful

Looks like my calculations are close, its not a huge saving for me, 40-50bucks a month...i wish Diesel were less than premium!

Aceman

That's a nice site with lots of information. It must change a bit because the side-by-side comparison I found at Compare Cars shows driving 15,000K / year.
GL 320 $2498
GL 450 $3302
GL 550 $3534

I think it's a function of how many miles you drive and what the price difference between diesel and Premium is in your area. For me at 18K / year and <5% difference, it pays off.

Prices are good south of the border. In Toronto diesel is US$4.10 per US gallon and Canada is an oil producer.

Unleaded is somewhat cheaper.

Wait 'til summer--diesel will be pretty close to price of regular, if not below.

You have to average prices for a year, not just decide based on prices at a point in time, especially winter.

I average 17.4 in combined city and hwy driving in the last 10,000 miles. Are you CDI guys averaging 24 - 26.1 city/hwy mixed driving? That's way better than the CDI is rated.

New EPA on the 450 is 13 City, 18 Hwy, 15 combined
New EPA on the 320 is 18 City, 24 Hwy, 20 Combined

Your 450 seems to be exceeding EPA ratings as well. My 320 is getting 22 combined but has never achieved 25 as some others have reported. However, I assume it would be possible for them to exceed the EPA ratings, as yours does.

More taxes for you guys on fuel, yes?

Every diesel I have driven has done exactly as you described. There is a threshold of efficiency and if you cross it, the economy drops off. On my last two trucks this has been around 70. I haven't determined where it is on our GL 320 yet, but I would assume it to be similar to yours.

If these MB diesels are anything like the ones in US trucks, one of the largest values will be realized at resale.

With the great MPG on the GL 320 I am finding it interesting to look at the MPG on mine - I pay close attention to it and have noticed a sharp drop off on efficiency when going faster, just as ScottyB has.

I have 8500 miles on mine and find that after about 64 mph the MPG drops from about 23.5 / 24.5 down to about 20-21. I like to go faster but also like the awesome MPG when taking it a bit easier. I only look at the trip computer and don't try to calculate it on my own.

I guess it gives me something to think about during my safety stops at a depth of 15-18 ft...

So all the GL 320 owners if you cruise at 80-85 mph for a long trip what do you get? Thats usually what I crise at is in that range.

I wonder if the GL 450 and GL 550 loose the 18 mpg rating at 80-85mph.

I know the EPA estimates use 80mph as a highway speed when they calculate the mpg for all the vehicles sold today.

As you are doing your safety stop, and after you get done calculating your MPG, you should calculate your SAC rate.

Currently in Australia, diesel is worth $1.48 per litre.
That works out to be $6.66 per gallon, Australian dollars.

US$3.19-$3.29 per gallon. I have not filled the tank yet - no additives right?

I'm very used to adding a container of Techron every 3K miles in the W221.

I wouldn't use an additive myself until I was sure it was ULSD #2 compatible. Even then, most additives are pretty useless based on what I've read.

BTW - $3.23 9/10 at the Pilot at Exit #1 just inside Arizona on I-10, east of Blythe. Sign price was $3.31 9/10 but then it was the lower price for "automobile diesel" (as opposed to what, truck and RV diesel?). Still #2 ULSD, though. Weird.

Filled up tonite US$3.559/gallon - ULSD in Southern NJ.

Yesterday in Fresno, Conoco 76 credit price was $3.79 premium and $3.99 diesel. Many stations are charging a dime more for credit.

USLD $3.52 yesterday for my F-250SD ... $98.56 !!

$3.79

Just went up $0.10 in Nashville to $3.59

Filled up today @ $3.599. Total $85. Ouch!

If diesel was the same or less than premium i'd be on it. Just dont get it.

Aceman

I have also noticed several filling stations charging for credit card use. It was a common practice as I recall in the 90's, then it seemed to go away for several years. I wonder who comes up with this ?hit?

On Feb 18, a large refinery (70K barrels/day) exploded in Big Spring, TX. Within hours thereafter, prices started going up. S&D works in mysterios ways. Although the stations were selling fuel they had purchased at the lower rate, they began charging prices on speculation. This refinery probably had no direct effect on the west caost but due to S&D, the deficit is felt everywhere. It is kind of like when O'Hare is shut down due to weather.