Fuel Efficiency: Missing the simple things?

[Peakster]

I've owned my Geo Metro for 3 months now and put on 8500 miles.

I've owned plenty of other cars and I've achieved great fuel economy with them. Some examples:

1). 1985 Pontiac Fiero 2.5L auto. EPA Highway = 31mpg. Driving 55mph in real life = 37mpg
2). 1991 Ford Thunderbird 5.0L auto. EPA Highway = 24mpg. Driving 80 mph in real life = 25mpg
3). 1997 Ford Escort Wagon 2.0L auto. EPA Highway 34mpg = Driving 55mph in real life = 40mpg

So what's with my Geo Metro? When I drive 55mph in it, I'm lucky to get slightly over the EPA highway of 49mpg. Natural Resources Canada rates my car at 66mpg (55 miles per US gallon) and there's no way in hell I can reallistically attain those figures.

So for the past while I was thinking that my unimpressive mileage was due to the lower outdoor temperatures, my higher rolling resistance winter tires, even my fuel cap that doesn't make the 'whooshing' when its opened.

But now that I'm really stumped, perhaps my car has some other deficiency? Things such as:

1). Spark Plugs? My car has 146,000 miles on it and I wouldn't be surprised it the spark plugs have never been changed.
2). Fuel Filter? Again, perhaps never changed.
3). Engine timing?
4). Anything else?

I guess my question to other Gassaver members is "Are little things such as spark plugs, fuel filters, etc. items that can decrease fuel efficiency to a noticeable degree? Or is the Geo Metro one of those cars where the EPA ratings are difficult to achieve compared to other cars?"

[JanGeo]

Assuming it is a manual transmission - change the oil in it. Plugs don't matter much unless you find the gas pedal getting mushy (plugs missfiring) when you push it hard - I went 90806 miles on the original plugs and only gapped them a couple of time in all those miles. Also check the alignment of the tires although the rear doesn't matter much - check for tire wear. 49 is pretty good an donly a little bit of coasting will get higher than that. Cold weather presents more dense air to push through thus increasing drag. I drove in single digit temps one time and couldn't get over 60mph unless going down hills. Another thing you could do is advance the timing a little if you can.

[Peakster]

Originally Posted by JanGeo

Assuming it is a manual transmission - change the oil in it... Also check the alignment of the tires... 49 is pretty good an doing a little bit of coasting will get higher than that... Another thing you could do is advance the timing a little if you can.

Perhaps I should just take it into my mechanic to get it an overall checkup as the Geo hasn't seen the shop since I've taken ownership. How much of a timing advancement is optimum?

I take it that Wal-Mart doesn't change Manual Transmission Fluid as their technicians keep writing 'N/A' in the 'check transmission fluid' catagory. I had no idea that changing it was possible.

The thing that's most frustrating with my car is that I do 30mph in 5th gear all the time (according to metrompg.com, that in itself should return 75+ mpg) while driving in the city. I also turn off the engine when coasting and stopped at red lights only to have little if any mpg improvement.

A Scanguage would probably be most helpful to figuring out what exactly my car is doing, but the hefty price tag is not helping.

[LxMike]

check out metro's site completely.

[red91sit]

Might want to check on the o2 sensors, they're usually the cause for bad mileage.

Air filters can also affect it, the timing and such are more of ways to increase the mileage. Fix the problem first, (if there is one) before trying to improve gas mileage in other ways.

[Compaq888]

My car is like that. The epa is 34mpg combined and my average is 40mpg. Even with the scangauge the best I can pull off is a 42mpg.

I think little stuff like plugs, filters should help. I have yet to still do an alignment and change my tranny oil, my air filter has never been changed. I can probably get .5mpg from that alone

Just keep your car in tip top shape and it should be fine.

[JanGeo]

Funny but I have never changed the air filter in my cars except for my Rabbit once in 163k miles - didn't really do anything. It all is compensated for by the fuel injection. Only think is to try some acetone and Torco GP7 in the gas - I used to run Marvel oil and STP gas cleaner in teh gas and it seemed to help a lot - top cylinder lubrication. The Tranny oil is a drain and fill - should be a drain plug somewhere on the bottom and a filler plug in the top - I think I added some Slick50 gear lube in the neutral switch hole after I remove the switch plug. Friction is the enemy - yor rear wheels should spin really easy and keep spinning like a bicycle. My brother didn't think the bearings were tight enough on my Geo but it was fine. Actually I could never get the bearing caps off to adjust them.
The timing advance I think I kicked it up about 3-5 degrees - just watch out for the distributor bolts - I snapped one off and had to leave adjusting alone after that. Check your front brakes for dragging they can really suck up gas if they drag even a little.

[rh77]

Originally Posted by Peakster

I take it that Wal-Mart doesn't change Manual Transmission Fluid...

Just an opinion followed by fact, but Wal-Mart uses poor mechanical practices and sells the same products as others, but they've been manufactured with lower QC standards. For example a Goodyear tire from "Bob's Garage" is the real deal, but Wal-Mart struck a deal to mass-produce a bunch of cheap Goodyears to sell, well, cheap.

I recommend finding a local shop -- get the word on the street. Ask around and find a shop with ASE Certified Mechanic. If you establish a relationship, you can get to know your car better through a friendly service person. At a "Big-Box" store, you can't even go look at the car when it's up on the rack because of "Insurance".

On a completely separate note, I experimented restrticting the intake hoping that less air would reduce power and fuel consumption. It turns out that it just reduced power. When people say to change their air filter (EPA, etc.) to save fuel, I'm not sure where this comes from -- unless the loss of power makes people hit the gas more to get the same results over time...

LSS, don't assume anything unless you have records. Not sure if the timing belt causes valve lash when it fails (someone chime-in here), but I'd check that for longevity and to get the timing right anyways. Plugs, wires, distribution system, fuel filter, clogged catalytic converter, all friction-related fluids, etc., should be checked. Tire pressures, driving style -- it could be a variety. It might take a professional to diagnose...

RH77

[Compaq888]

Walmart is stupid. One time me and my uncle went to get a tire changed. We dropped off the wheel and it was ready like in 10 min. We come up to the guy in the auto department and tell him that's it's ready and we would like to pay. The dude was so drugged up on drugs it was unbelievable. He could barely muster up a complete sentence. We went to the superviser and the he was out of it too. Took us 20min just to pay for the damn tire.

Drugs are bad. If you're going to smoke or pop some pills don't come to work.

[GasSavers_Ryland]

check out your owners manual, it should give you a chart of things to check and change, a vauge idea of how often it's recomended that you do them.
I would sooner trust someone in a grocery store parking lot to check over my car then a teenager at wal-mart's car center, I've met a few of them, and I had to wonder if they made a habbit of sniffing tail pipes, or what.
Just change your spark plugs, it will cost you about $6 total, another $10 for an air filter, pick up a can of carb/intake cleaner, and clean your intake, and your PCV valve.
Other then the time, it's practily free to jack up each wheel, spin it, wiggle it, look for drag, and for exsessive play in bearings and brakes.
Without a scangauge, or some other feedback device, I wouldn't drive in such a high gear, yes, you can drive very carfully in a high gear, but even the slightest nudge of the gas pedal could make it dump extra gasoline in, making it run less efficently, and making your mileage drop.