[Vwdiesel] Fw: Mileage test of Rabbit 1984 --- ( Smileage (fwd)

Val Christian val at mongobird.com
Fri Aug 5 07:06:01 EDT 2005

I have lots of different pieces of fuel economy data spread about,
but here's one set of tests we did with a 79, in 1980, which gives you 
a flavor regarding the sensitivity to speed:

40 mph		64.25 mpg
45 mph		63.39 mpg
50 mph		58.25 mpg
55 mph		53.12 mpg
60 mph		51.38 mpg
65 mph		49.36 mpg
70 mph		44.37 mpg
75 mph		42.06 mpg
80 mph (WOT)	40.41 mpg

Notes from this test:

1. Done on flat sections of NY 17.   (now I-86)
2. 1/2 gal of fuel burned, then miles traveled measured.
3. Speed by speedometer, miles by odometer.  SD of 0.08 miles 
against highway markers (pre-GPS days!).
4. Outside air temp varied between 45F and 62F during tests.
5. Wind below 10 mph, and predominantly crosswind.
6. Air filter changed immediately prior to test.
7. Oil 20W-50 Castrol 
8. Windows closed, fan off, interior vents open.  Three wire antennas
on roof (2m 5/8w, 20cm center loaded dipole, 2m 1/4 wave).
9. Tire inflation 35 psi on all tires.  (Mich. XZX tires)
10. Driver wt. 240 lbs, no pax.  No spare.  About 30 lbs of radio 
equipment beyond stock Rabbit.
11. Odometer 31330 at start of test, original engine, no mods.
12. 80 mph run did not maintain 80, sometimes 77 was max, 82 was upper limit.
13. Miles are US, and gallons are US, #2, same fuel batch.
14. 4 speed transmission, 4th gear used for all tests.

At that time, we did a bunch of testing, but this day's testing was 
aimed at getting data points on burn vs. speed.  There were several other
burn vs. speed runs what were done.  There were also parallel runs, 
air dam on/off runs, etc.  I've got a couple of lab notebooks on experiments
we did.  For the high speed runs, the chase car was about 3/8 to 1/2 mile
ahead (in radio contact).  For the low speed runs, the chase car was behind,
with flashers.

If we did this today, with a TDI, we'd use the flow figures from the computer,
and timestamp them with GPS.  Then we could post-process using the GPS
time-distance data, and lay the data onto DEM (digital elevation model) to
obtain gadient data, and adjust for slope of the roadway.  We could also
smooth out the burn data.  


Forwarded message:
> 24.2 Km and fuel used 1.2 Litres.    second run  02 Aug
> >2005 ---
> >>15.4 km and fuel use 0.75 Litre.
>   That's 52mpg @ 50mph to 56mph and just over 48mpg city (US MPG.)
> I think that's 62.4 and 57.6 imperial.  My Rabbit used to do close to that, 
> pedal to the floor driving style, back when we had the 55mph limit.  Doesn't
> do that with 60mph and higher limits.  Still fun though!  :-)
>      Loren

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