In article <wFrlf.1982$PX2.firstname.lastname@example.org>,
> Hi all,
> I've got a trusty '87 760GLE with a B280F that seems to still keep on (lets
> not say ticking, cuz thankfully it is not!!) running.
> I'm at 290K kms (181K miles or so).
> My daily trip to work is 50 kms one way. During the summer I can expect to
> use 10.75-11.5 L/100kms of fuel. I'd get a total of about 450km per
> tank/47L or so fill. So roughly, I drive 10km city and 40km hwy during my
> drive to work, then back home.
> So winter is here, and I have my Pirelli Winter Carving winter tires on...
> it's below 0 C and now my fuel consumption has shot up to 13.5L/100km NO
> matter how easy I am on the throttle. The best I've done is 13L/100....
> woa.. from 10.75 to 13?? that big of a difference?? Now my tank gets about
> 350-380 km or so range. (I guess it works out to be 22 miles/gallon during
> the winter).
> Is this about right? I love the car, but I'm travelling myself, and I
> really wish I had a more fuel efficient car...
> Honestly, I'd feel just as safe if I was driving a Toyota Echo hatchback.
> I've raced cars for 10 years, have driven big and small, and if a transport
> truck slams into me on my way to work.. well, I don't think my 760 is gonna
> be any safer than a modern small car with air bags. BUT I do like the 760..
> don't get me wrong :).. I love RWD too!!
> So, any other 760 B280F or B28F owners out there with some observed fuel
> consumption?!? (BTW: I typically travel about 110km/h steady at highway
> speeds. Got the AW71, no brake drag, good tire pressure, good alignment,
> everything should be good to go. Diff seems good, no dragging/worn
> bearings. ....
I'm guessing you're posting from Canada and I'm not sure about the
engine configuration there. To me Canadian models are quirky, sometimes
delivered as Europen models and sometimes as North American models. So
the information given is more generic then model specific.
The biggest mileage killer would be a lazy or inoperative (stuck open)
thermostat that would cause the fuel injection control unit (if it has
an electronic fuel injection fitted) to run excessively rich. If it has
the K-jet system fitted the control pressure may be staying low due to a
burned out heater on the control pressure regulator. A similar effect
could be produced by an inoperative heater circuit on the O2 sensor or
simply an O2 sensor sorted to ground from excessive carbon build up on
the sensing element, if you have one. A low or aged battery will force
the alternator to work harder longer thus adding power losses during the
warm up period when the engine is consuming extra fuel.
Low or insufficient tire inflation pressure will induce excessive drag.
A higher profile tire (i.e. larger circumference) will yield fewer miles
on the odometer than the tires previously installed and produce a larger
number when doing the consumption calculation.
Switching to synthetic oil in the motor and differential will give
noticeable improvement in consumption. At 60-65mph (~100 kmph) you
should see a drop of about 100-200 rpm for the same speed.
If you know the exact mileage recorded between two points as logged on
summer tires, compare it to the same mileage as logged by the winter
tires over the same distance to rule out a distance measurement error
before checking the engine performance parameters.
The goal when driving is to miss the maximum number of objects.