Modern Electronics & Fuel Economy:

[Doktor Bert]

Funny,

I have been driving this 300SD for almost 20 years and 22-27mpg is about the best it will do, with 25 mpg being a very common average figure.

When I drove my 2001 Mustang 4.6 V8 to Florida a few months ago, I was knocking down 27-30 mpg on a consistent basis, over a 6,000 mile journey, and that was running the A/C all the way there and back.

I have heard many people claim 35 mpg from a 617, but I have never seen one net more than 30 mpg personally.

I guess chalk one up for modern engine management???

[oldsinner111]

I regularly get 30 around town and 32 on highway.Once I use a 25% ATF used with diesel and got 37 mpg

[Doktor Bert]

Originally Posted by oldsinner111

I regularly get 30 around town and 32 on highway.Once I use a 25% ATF used with diesel and got 37 mpg

5 cylinder????

The ATF must have really raised the cetane rating.....

[oldsinner111]

yes sir 1983 SD.

[Doktor Bert]

My Dad's 1982 300SD with a brand new engine gets about 25 mpg.

[LandYaghtLover]

The Ford 4.6L can be a very efficient engine. My Lincoln could get 32mpg highway. And thats a bigger, heavier car than my benz!

[Doktor Bert]

We had a 750il that got 25 mpg on the freeway running the A/C. Hated the car, but loved the engine. I have my eye on an 850csi with a 6 speed at present, but not bying it for economy....

[rscurtis]

Don't overlook the advantage of overdrive transmissions and locking torque converters. Also, our older cars were geared for the 55 MPH speed limit in force at the time. Old, pre-combustion style engines don't help either. My '03 Dodge PU weighs twice as much as my 300D, has an engine twice the size, 2.5 times the HP, but will still return 75-80% of the car's highway fuel economy at 65 MPH. At 55 MPH, the difference would be even less.

Current fuel economy would be even better if cars weren't loaded down with thousands of pounds of useless junk.

[scottmcphee]

A lot of that new weight is not useless when it's serving a safety purpose. However there is a lot of crap too, changing cars into info-tainment systems and nanny controls (doing your driving job for you).

There are lots of areas on our old Benzs where newer inventions and electronics sensors could be retro deployed to save big on bloat weight. Here's a couple that jump to mind: tilt sensor (anti-towing) for car alarm, intake air flow metering... Consider also what vacuum actuated door locks add up to with the aux vac pump under rear seat. A power antenna. This list could go on...

I have box filled with stuff like this, including the egr delete, all the vac pods for emissions, etc.. Probably fifty pounds of junk.

It's always interesting to see what new cars are doing to shave weight... The pains they go thru to gain 100lbs of lightness back.

And where they add stuff that pays itself back, such as grill shudders, which are becoming more common.

[Diesel911]

Originally Posted by rscurtis

Don't overlook the advantage of overdrive transmissions and locking torque converters. Also, our older cars were geared for the 55 MPH speed limit in force at the time. Old, pre-combustion style engines don't help either. My '03 Dodge PU weighs twice as much as my 300D, has an engine twice the size, 2.5 times the HP, but will still return 75-80% of the car's highway fuel economy at 65 MPH. At 55 MPH, the difference would be even less.

Current fuel economy would be even better if cars weren't loaded down with thousands of pounds of useless junk.

On gassers in the 1970s they claimed that if you could get rid of 400 pounds of vehicle weight you could raise you could gain 1 mpg.

[Doktor Bert]

Originally Posted by Diesel911

On gassers in the 1970s they claimed that if you could get rid of 400 pounds of vehicle weight you could raise you could gain 1 mpg.

Throw out the passenger....

[Doktor Bert]

Yes, the overdrives are a big part of economy. The 3.07:1 axle in my 300SD has me turning a whopping 3,000 rpm @ 70mph.

The proposed 2.47:1 axle will drop that to a paltry 2,400 rpm @ 70 mph!

[MBeige]

Aerodynamics play a huge role too.

I noticed a lot of American cars have low highway RPMs.

[barry12345]

There is little to no doubt that over the years fuel management and delivery systems have been subject to extreme improvements. There is not a lot than can be done with the older indirect delivery injection engines.

Worse of all when they were designed fuel was very cheap and no imputus to get the best possible milage extracted. What they delivered milage wise did not hurt their sales back then in my opinion. Many gas fuelled cars only got around ten miles per gallon then. So they seemed pretty good with the gas cars as a baseline at the time.

[oldsinner111]

I noticed a lot of American cars have low highway RPMs

Alot have those 6,7,an 8 speed transmission,that won't take much real horsepower.