doug@edge.UUCP (05/16/87)
> It is generally a well known fact that if you drive a car using the > accelerator a bit like an On/Off switch then you are very likely to waste > fuel. The most economic driving style is gradual acceleration and > gentle braking. Generally well-known, but a "fact"? I'm not so sure. Holding a constant cruise speed by flapping the accelerator up and down is obviously stupid, and the economics are (to me) unimportant. And I don't see that braking gently saves any more fuel than leaving four big black marks on the street (although the latter is a bit rough on the tires, which aren't much cheaper than fuel these days :-) But I have seen many references that the old "drive as if there was an egg between your foot and the gas pedal" method is an inefficient way to accelerate. These references suggest that the proper thing to do is to smoothly depress the accelerator pedal to the floor (not jab it to the floor). Shifting should be done at the lowest practical RPMs. I don't know how reliable any of these claims are. I do know that I use full-throttle acceleration, and I usually get about 1 mile per gallon better fuel mileage than my wife does from the same car. And I have a lot more fun when driving :-) -- Doug Pardee -- Edge Computer Corp., Scottsdale, AZ -- ...!ihnp4!mot!edge!doug
jnp@calmasd.GE.COM (John Pantone) (05/18/87)
In article <759@edge.UUCP>, doug@edge.UUCP (Doug Pardee) writes: > But I have seen many references that the old "drive as if there was an > egg between your foot and the gas pedal" method is an inefficient way to > accelerate. There are two very distinct "versions" of efficient, when applied to acceleration in an automobile. Version 1 - use minimum gasoline Version 2 - use minimum time Neither version can be solved, as a general rule, by holding the accelerator in one position. Automobile engines have a "best-gas-milage" rpm and a "best horsepower" rpm. They can be, but usually are not, the same. Maximizing either version requires modification of accelerator position with reference to manifold pressure, vehicle speed and engine rpm. Automatic transmissions are actually fairly good at this sort of thing (or can be anyway). Perhaps the "drive like you have an egg between your foot and the accelerator" arose because given no tach, or manifold pressure gauge, and an automatic transmission at least this would let the trans. do most of the decision work. -- These opinions are solely mine and in no way reflect those of my employer. John M. Pantone @ GE/Calma R&D, Data Management Group, San Diego ...{ucbvax|decvax}!sdcsvax!calmasd!jnp jnp@calmasd.GE.COM
beede@hubcap.UUCP (Mike Beede) (05/19/87)
The reason for the old saw about abrupt accelerator movements
is that opening the throttle abruptly causes extra gasoline
to be introduced via the accelerator pump. This enrichment
of the mixture keeps the engine from bogging down--as you
will notice if it ever packs up. If the pedal is moved
slowly, the extra gas doesn't get introduced (there is
another passage for it to escape from which doesn't
lead into the throat.
Barring this, carburated engines are more efficient when
there is less restriction by the car, i.e., at full
throttle.
I will thicken my skin waiting for net auto mechanics
correct this ##) <--smiley with hockey mask
--
Mike Beede UUCP: . . . !gatech!hubcap!beede
Computer Science Dept. ARPA: BEEDE@TECNET-CLEMSON.ARPA
Clemson University INET: beede@hubcap.clemson.edu
Clemson SC 29631-1906 PH: (803)656-{2845,3444}coleman@sask.UUCP (Geoff Coleman @ College of Engineering) (05/24/87)
> >> It is generally a well known fact that if you drive a car using the >> accelerator a bit like an On/Off switch then you are very likely to waste >> fuel. The most economic driving style is gradual acceleration and >> gentle braking. A couple of years ago there was an article in a Road and Track that stated that BMW's engineers in tests had showed that the best mileage occured when they accelerated cars to speed as fast as possible. It also showed that shifts at 2000 rpm were better than at 5000. This test suprised everyone especially the engineers invloved. As well I work for the Engineering College which at present are the World fuel economy record holders. Talking to the different people in the vehicle research group you can get a number of different (and contradicting) oppinions about how to increase economy on a bought car. -- Geoff Coleman | BITNET: Coleman@sask College of Engineering | UUCP: {utcsri,ihnp4}!sask!skul!geoff University of Saskatchewan | Compserve: 76515,1513 just a number Saskatoon, Saskatchewan | voice: (306) 966-5415
moto@ucbcad.berkeley.edu (EDIF Committee) (05/26/87)
I dont know how relevent this observation is to auto driving, but an aircraft always uses maximum sustained power when climbing to save both wear on the engine and for fuel economy. Note that this is usually LESS than takeoff power since that is not sustained. Mike