camary gas mileage strangeness

I kept a detailed record of the gas usage and mileage on my Camry when I drove longer miles before. At these days, I drove slowly at 57-60 MPH and I got an average of 37.61MPG for a period of 1 year and 2 months. It was roughly 25% road and 75% highway driving. Then I didn't record the mileage for about 2 years. I started recording the mileage the last half year since I travel between 2 cities frequently. My MPG has dropped to 32MPG in average with roughly the same 22% and 78% highway. I also noticed that the way to get a higher gas mileage has changed. The ideal speed used to be between 55-60MPH, but now it needs to be a little over 70MPH.

Compare the MPG at different speeds (from a trip of ~160 miles):

62.5MPH - 29.49 to 30.11 MPG 70 MPH- 32.95 to 33.46 MPG 72 to 73 MPH- 33.19 to 35.56 MPG

So basically, the faster I go the less gas I use as opposed to the old days I got more driving at 57.5MPH. I never tried faster but I think MPG would drop if I go faster. The only thing I can think of is that I changed the spark plug which is Bosch 2 ground electrodes before I started recording my mileages this time instead of the 1-electrode ones that I used before.

So do you think that different spark plugs generate different gas mileages and it has different optimal performance at different speeds? I've not changed my gas filter to tell if that makes any difference.

My car is 1994 4 cyl. Camry with ~108,000 miles on it. It had 60K to

70K miles on it when I recorded the 37.61MPG.

Any suggestions on getting more MPG out of it. It still runs well, and I hope to get another 100K out of it.

Thanks,

cpliu

Reply to
cpliu
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Could be down to the age of the car. I've had enough trouble with Bosch plugs to replace them with anything else when I suspect a problem. Maybe the fuel has changed subtley.

Reply to
jg

The faster you go the less mpg you get....... Max mpg is apx 40 mph, just when the over drive shifts. As to getting less mpg a year later, well sure, parts wear, a stretched timing belt cost me 4 mpg, till I reset timing. Plugs, wires, cap, rotor, coil, all increase resistance with time, your O2 sensor, engine compression , and many more things need regular maintenance. Also different season gas formlas play a big part. But you dont get more Mpg going faster, it was something else afecting it, maybe the Gas. In the midwest winter formulas lower mpg by apx 2 mpg, and formulas have changes over the years many times.

Reply to
m Ransley

It's puzzleing to me too but the fact is I did get higher MPG when driving faster. It's the same car, same gas from the same gas station (BP or Shell). Everything else is equal except I drove faster in later trips.

1) Trips happened in the past winter. Temperature was not too much different. 2) The travel was about 300 miles when I filled up the gas tank. I did it for a period of time. So there wasn't too much margin of error.

I found similar result with a Honda Civic I owned. It didn't get as much MPG at 55 than 70. This is the first time, I got different results at different time on the same car. Before, I got 32MPG driving at

70MPH; > 35MPG at 57MPG. Now, the same car got more when driving at 70MPH. If I get more gas mileage at 57MPG now, I would believe it's the aging of the car.
Reply to
cpliu

Who figures the milage, a computer or you, I would not trust the car computer, and this assumes you fill it the same way, and realy at the same pump, because how do you know you dont overfill it a bit. Either way what you state does not work, Energy needed is not proportional to speed, there are formulas, but the fact is on a given mile the faster you go art a point it just takes more gas. Or anopther way to look at it it may take 15hp to go 50 mph, but 75hp to go 100mph. The faster a motor runs the less efficient it is.

Reply to
m Ransley

overdrive kicks in at 48 mph on my 06 camry 4 cyl. at 50mph rpm is

1800. my 97 corolla also kicks in final gear at 48 mph but don't know the rpm since the 3 speed auto doesn't have a tach.
Reply to
Dave Dave

Could be a difference in Tire type or even tire pressure

Reply to
sqdancerLynn

Reply to
toyotadaddy

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