dave@ihu1f.UUCP (11/07/83)
I have carefully monitored gas mileage for 5 years. The best gas
for mileage that I have found is actually a mixture.
Here is what I have found:
1. Too low of an octane will cause pre-ignition detonation
(combustion chamber "knock") before the power stroke is over.
The result is less mileage/gallon.
2. Too high of an octane will not knock, but will not finish
burning in the combustion chamber before the exhaust valve
opens. The result is less mileage/gallon.
Therefore, to maximize gas mileage, you must find an octane
combination and engine timing that will knock only under heavy
accelerations. When an engine occasionally knocks a little, you
are getting the best mileage.
The mix that I find works the best is when your tank is half full,
first fill it with Shell 89 octane. Next time, fill it with Texaco
91 octane. Watch out for ethanol in Texaco, your car won't start
when it is below 20 degrees.
Finally, for 5 years, my gas mileage always goes down in the
winter, not because of the choke, but because of the de-icer
additives in the gas.cwa@ihuxm.UUCP (Carl W. Amport) (11/11/83)
I agree with Dave Miller's comments on timing/knocks/octane/mileage but I don't think gas with ethanol should hinder starts in cold weather. In below zero temperatures, products such as HEET are added to gas tanks to help evaporate water that is condensed out of the air by the subzero temperatures. Often, a cold car that will turn over but not start can be started after adding HEET and waiting a few minutes. HEET can also be used as a preventive measure but keeping a full tank is adequate in all but the coldest weather. HEET is mostly alcohol (ethanol?). I would appreciate other comments and information about ethanol and cold weather starts. In other words, correct me if I'm wrong. Carl Amport Naperville, IL.
rls@ihuxf.UUCP (Richard Schieve) (03/16/84)
1980 Turbo-charged 4 cylinder Mustang (1600cc). 20 mpg city, 27 highway, these are consistent figures over 3 years. 1969 Camaro, 350 cid v-8. 13 city, 16 highway (it might be better if I could keep my foot out of the carb!).
pmr@drufl.UUCP (Rastocny) (03/17/84)
I kept pretty accurate mileage readings on the last few cars I owned so here goes: 1972 Honda 600 sedan after 65K city/highway miles Lowest: 28 Best: 55 Consistent average: 40 1978 Plymouth Horizon after 42K city/highway miles Lowest: 25 Best: 36 Consistent average: 32 1980 Subaru 4x4 wagon after 110K mostly highway/mountain miles Lowest: 22 Best: 34 Consistent average: 30 (This car still has the original battery, fan belt, rotor, distributor cap, plug wires, water pump, etc. I've only changed tires, oil and filter, wiper blades, and bulbs.) 1982 Subaru 4x4 wagon after 78K mostly highway/mountain miles Lowest: 24 Best: 37 Consistent average: 32 1984 Subaru 4x4 turbo wagon after 3,200 mostly highway/mountain miles Lowest: 20 Best: 26 Consistent average: 24 (This car has a bad wheel bearing that will get fixed next week. Mileage will probably go up a bit.) Phil Rastocny
prophet@umcp-cs.UUCP (03/17/84)
1979 Datsun 310GX, 5-speed, no airconditioning:
Highway: Best: Worst: Average:
59.9 36.5 43.7
City: Best: Worst: Average:
35.5 23.1 28.0
That "Best" figure in the highway driving (59.9) is NOT a typo. I have managed
to obtain this figure or a figure very close to it by using special driving
techniques. I have kept mileage records for this car since the day it rolled
out of the showroom in June, 1979. What's more, most of the highway mileage
comes from a commute that I make between Washington DC, and Richmond, VA,
which is 125 miles, and a trip that I make quite frequently. What I really
can't seem to figure out is that this is the only car I have ever been
associated with that CONSISTANTLY does better than the EPA estimates (27 City,
38 Highway). I have been using synthetic lubricants in both the engine and
transmission, which might have helped a little....
Dennis
--
Call-Me: Dennis Gibbs, Univ. of Md. Comp. Sci. Center.
UUCP: {seismo,allegra,brl-bmd}!umcp-cs!prophet
CSNet: prophet@umcp-cs
ARPA: prophet.umcp-cs@CSNet-Relayhstrop@mhuxt.UUCP (trop) (03/19/84)
Regarding gas mileage: 1980 Saab Turbo (3 door) 22-25 city 30-33 highway (at 60 -65 mph) 26.4 highway (at 90 mph avg, at 2 am) 1983 Saab Turbo (3 door) 23-26 city 30-32 highway (at 60-65 mph) 1962 Ford Falcon Van (160 cu in engine, 3 speed manual) lowest 11 mpg (leaky fuel pump) city avg 17 mpg highway avg 21 mpg highest 28.7 mpg (avg 50 mph on I-5 in spring fog) By the way, the old Ford Falcon Van has 210,000+ miles on it, and is still running. My father uses it to haul wood and trash, mostly. It survived 4 transcontinental round trips, 5 excursions into the wilds of western Canada, and the worst test of all, 4 yrs in Boston, Mass! Harvey S. Trop mhuxt!hstrop
steveh@hammer.UUCP (Stephen Hemminger) (03/19/84)
I keep pretty good records, but mileage flucates: '81 Diesel Rabbit (4 speed) [Americain version] Low: 36 High: 52 Average: 43
sdo@u1100a.UUCP (Scott Orshan) (03/19/84)
What happened to the net rule that queries are answered by mail,
with the originator of the poll posting summaries? In the case of
a topic for discussion, followups are appropriate, but this was
a simple survey to collect facts. Remember that each article has
a multi-line header, and a signature, which take up as much space
as the article itself. It is much more efficient to mail replies
to the originator, who can organize them by car type, and present
the results to all of us.
These are very useful facts which I'd like to know, but I can't
read every article about gas mileage when there are dozens of them.
Scott Orshan
Bell Communications Research
201-981-3064
{ihnp4,pyuxww}!u1100a!sdo