fox (12/03/82)
#N:zeppo:5300006:000:3014 zeppo!fox Dec 3 08:42:00 1982 Having seen and heard many arguments for and against 55 MPH on the net and elsewhere, most of which contain references to "they..." or "statistics show...", I am posting the results of a mpg experiment. TRB's request for info was one of the prompts for this, my first article to the net (be gentle). In 1980, I experimented with a series of trips at various speeds and recorded the gas usage and conditions. As follows: 1979 Honda Accord, 5 speed, 10,000+ miles, synthetic oil, Exxon regular gas, windows closed, heating and vents open, driver only, a few pounds of food and drink in car at start and decreasing after start, tire pressure checked at beginning of trips, trips in February, similar temperature, similar terrain, on interstate highways, no unneccessary stops uncertain about winds, An error margin of +/- 1 is probably reasonable on all data numbers. 45-50 mph, 37.4 mpg, a single trip which involved 4 fills of 13.2 gallon tank one way, (Before I get any flames for going so slow, there was minimal traffic on the road, and people always passed me without honking or other expressions, this was between NJ and Ohio.) staying in 5th gear when possible, freewheeling occasionally if no other traffic, downshifting to 4th gear for hill climbing (to prevent damage from lugging and to maintain reasonable speed ) 72-77 mph, 34 mpg, same trip involving 4 fills of tank one way, (Before I get any flames for going too FAST, I passed 3 radar traps and I was never pulled over, so either the bears were asleep or they thought my speed was reasonable.) always in 5th gear, no freewheeling since the car slows down too much, constant throttle 55-60 mph, 29 mpg, over many more than 10 fills, this was more or less my regular driving pace, 5th gear, constant throttle The constant throttle business: Some literature that I have read state that driving at constant throttle improves the mpg. Of course, when I claim to have driven at constant throttle, I mean I 'set' the speed on a level road and tried to keep my throttle foot at the same position until the next flat stretch where I corrected any change I might have inadvertently made. The experience from this trip pointed out to me some factors which I never really thought about: 1. driving slow calls for many more stops as my need for metabolic transmigration is more of a time function than a function of distance. 2. driving slow might keep me on the road pass daylight hours when I need to turn on the headlights.(lower mpg) Incidentally, the Accord got (it is now an accordion, I tried to stop a Mack truck at convergence speed of ~ 70 mph, the trucker survived) 32 mpg average over a year with regular gas. It was rated at, I believe, 26/34 mpg. It runs a little loud at 75 mph but was still comfortable and stable. These are real life trips in a particular car with a specific driver and not the result of simulated mpg experiments in a lab, or calculation of gas economy by measuring exhaust. Other experiences? zeppo!fox G. Moy