Most curious...

[altivo]

I drive a 1997 Jeep Cherokee Sport, with the stock 4 liter engine and manual five speed transmission. I like driving it, I like the flexible cargo space, I appreciate the 4 wheel drive in winter. (For those not real familiar with the Jeep line, this is the utility vehicle, more like a capped pickup truck than it is like a "Grand Cherokee" which is a lightweight performance SUV.)

Anyway, it has just under 80,000 miles on it and the nickel and dime maintenance is starting to be irritating. I was thinking about getting something new this summer, probably after the 2006 models are on "must sell" deals because they are loading up with 2007s. I have a CD maturing then too, so I won't have to borrow a lot of money for the deal.

But this morning I had second thoughts. We've all been grouching about the rising fuel prices. My big expense for a 400 mile round trip to Michigan last weekend was fuel. I used about half a tank going, filled up while I was there, and used half a tank coming back. This morning when I went for groceries I filled up again and as usual, wrote down my odometer readings on the receipt. Then I stared at them. This can't be right. Looked at the last few slips...

I'm a conservative driver, and I do usually get gas mileage right in the EPA rating range for the vehicle I'm driving. If I recall correctly, this one is rated 21 mpg city and 25 mpg highway. I haven't checked carefully for a while, and my rough estimates told me I was getting around 21 to 22 mpg on average.

On my trip to Michigan I got just under 30 mpg. (29.887 to be exact.) This can't be right, it just can't. But the figures have been double checked. That's nearly as good as my mate is getting with his 2005 Escort.

The only thing I can think of to explain it is that perhaps Michigan gasoline is not adulterated with ethanol? Here we get 10% ethanol by state mandate, which I don't mind, since it's a renewable resource and all that. But we pay the same prices I paid in Michigan, too. Could regular unleaded purchased in Michigan be that much better? It has the same octane rating, for what that's worth.

I admit, I'm a dummy about "infernal combustion." I know the general theory, but I prefer to pay someone to work on my engine when it needs it. I'd rather take a computer apart and modify it, and I understand that much better. But this just doesn't make sense to me. Maybe I should keep this vehicle longer after all.

Comments

[pioneer11.livejournal.com]

I dunno, you may just be getting that 30 mpg after all.

I remember from somewhere that the Sport version of the
Cherokee could get exepctional mpg but I'm not sure
where I heard it.

[altivo.livejournal.com]

Well, there are some other factors that may enter into it. Weather has warmed up to the point where neither the heat nor the air conditioning is needed, for instance. I've been grumping about 21 mpg all winter, but Illinois has a law about "winter fuel" that is supposed to improve air quality but supposedly gets poorer mileage. I don't know when the switchover happens between winter and summer for that.

On the other hand, I used to get 48-50 mpg on the highway with my '89 Geo Metro. That would look really good at today's gas prices.

[quickcasey.livejournal.com]

While the mileage you stated is a bit on the highside for your vehicle, bad gas here is partly to blame. The present tank on my full-sized van is just going out the tailpipe quickly. Michigan gas is of better quality, I found.

[chibiabos.livejournal.com]

I thought all gasoline was the same, just different detergents/additives?

[chibiabos.livejournal.com]

I'm getting better gas mileage out of my tanker guzzler Dodge than I thought, but nowhere near that good. I thought the Dynasty would only get 15-20 mpg, but I'm getting 23. I think I'm getting better than the vast majority of drivers would, because I do not exceed the speed limit ... 35 MPH speed limit to me means, *shock* *gasp* 35 MPH. Not 36, not 40, not 45.

I understand you are pretty similar in that respect, and most vehicles get their optimal MPG somewhere around 30-40 MPH, IIRC. Maybe that's a contributing factor to why you're getting better than expected MPG?

[altivo.livejournal.com]

It's true that I almost never exceed a posted speed limit and I don't waste gas and energy on aggressive passing etc. In the past I've found that I get the best mileage out of most vehicles at around 50 mph, actually, but under normal dry road conditions driving at that speed will drive you crazy with the tailgaters and aggressive passers making rude gestures at you.

Since I live in a rural area and almost all trips are over ten miles and at an average speed of 45 to 55 mph, I'm probably being real easy on the engine and getting optimal results. No steep hills here, either, just gentle ones. On the other hand, I take the long maintenance plan for oil changes, often going 6000 miles between since I don't do stop and go city driving.

Record gas mileage guy

[goldenstallion.livejournal.com]

Hi, Eagle.

I remember watching a TV show years ago which featured the Guiness World Record (why the caps?) gas vehicle mpg winner. The car got over 350 mpg. Of course it was a special, super-light, low-profile, super-streamlined car with a tiny engine and bicycle wheels but the main thing that impressed me was his driving style.

Start the engine, floor it, go to the top speed it would go to accelerating, cut the engine and coast to a stop. Do it again. And again. And again.

Not, exactly how we need to drive our daily cars of course but it always seemed odd that this is how to get your best mileage. Or maybe just in that, particular vehicle.

I agree that driving conservatively is a huge help. Most drivers hit the gas and accelerate fast up to over the limit then slam on the brakes when they have to stop. No, that is all wrong and it shows when they keep having to fill their tank and replace their brakes, etc.

Of course most Americans need a brain wash. Grin.

No, I have driven in Japan, Bolivia, Tunisia, Greece, Spain, Malta, etc. and everybody does it.

Steed

[captpackrat.livejournal.com]

Ethanol has only about 72% of the energy content of gasoline, so you have to use a lot more to regain the lost power. At a 10% ethanol/gasoline solution, that's about a 3% power loss, which is actually pretty substantial.

[altivo.livejournal.com]

That must be part of it, though a 30% improvement in efficiency on a tank of gas that was still half Illinois grade is rather unbelievable.

[goldenstallion.livejournal.com]

Dear Rider,

Remember, too, that a lot of that was highway driving as apposed to stop-and-go driving. My Pontiac Transsport gets around 25 on the highway (such as when I come to visit you) but only around 21 or so normally (a mix of highway and stop-and-go).

Perhaps there are differences in the gasoline and the ethenol additives but I kinda doubht that makes a big difference in mileage.

Imperator the impossible (fun to dream)

[pokeypony.livejournal.com]

Well im not really a fan of chrysler products of any sort from the 73-00 era because they are usaully pieces of crap with no resale value whatsoever and riddled with all sorts of quality control issues,but however of the few decent products they do have I must say the standard jeep cherokee,or even wrangler with the 4.0 and the 5-speed is the one to own and is a good vehicle if you can get over the irritating electercal and brake issues.
Sometimes you do get a vehicle that is just exeptional for whatever reason and it sounds like you have one so if I were you I would keep it until something major broke IE engine or major electrical.

The way you drive tho,and if you do keep all the fluids maintained it should last you for quite a while and the body will probably rust away to nuthing before you have any major mechanical issues.

Keep the oil changed,keep the transmission fluid and transfer case fluid and rear differential fluid changed and make annual extensive inspections looking for major rust on the subframes and ride it for as long as you can.

And if and when you decide to trade it in and get something else you would probably be happy with something like a suburu because they get exeptional milage and have all wheel drive for winter weather conditions and are reasonably priced as well.

[altivo.livejournal.com]

Yeh, but I'm used to getting about 25 mpg in highway driving. I'm guessing that it really is a difference in Michigan gasoline combined with the fact that I needed neither heat and defrosters nor the air conditioning on this trip. And of course I didn't drive over 70 in Michigan, so everyone else kept passing me at 85-90 and probably sucked me along for free. ;P

Darn it, I miss you two already. I wish it wasn't quite so far.

[aerofox.livejournal.com]

Many years ago, I took a trip down to Richmond Virginia with what I thought
was a tire out of balance (later found out it was a defective tire).

I could not go above 60 MPH without serious vibration, so I stayed at 60 the
entire way down.

now, this was my little 1989 Volkswagen Fox. I normally got between 30 and 33
MPG. but on this trip I was getting 38 MPG! I was amazed that driving 60 instead
of 70 would make such a difference.

now, my Cobalt doesn't seem to be affected by speed. in fact it seems to get
better gas milage at 75 MPH :P

Then there was my 1982 Mercury Lynx with its underpowered 1.6 litre
engine.... that sucker got 45 MPG!

[altivo.livejournal.com]

Definitely true. Back in the 70s, when we had the first gasoline price crunch (gosh, it got to over a dollar a gallon and people swore they were going to stop driving if it went higher) I had a VW Beetle, a 1973. Speed limits were still 70 and I experimented with sticking to 55 whenever I could. It made a significant difference. Of course, then the federal government enforced that universal 55 mph limit and everyone got all mad about it. They didn't like the gasoline prices but they wanted to be able to waste as much as they felt like.

I noticed last weekend while driving that the much higher prices right now don't seem to be slowing down the people who drive those huge bus-like campers and tow a car behind them. There were plenty on the road. I don't know if Americans really are that wealthy or if they are just stupid and charging all their credit cards up to the max all the time. I do neither, so I just go without a lot more often.

[goldenstallion.livejournal.com]

Oh yea,

As speed goes up, gasoline or deisel consumption goes down. Exponentially.

Another thing is that as you go faster and have an accident... it is also exponential the damage and harm it does to you.

I am betting that in the near future we will have National 55 speed limits again. Gas lines. Limits on how much you can buy at the pump at one time.

Like in the seventies.

I drive the speed limit or, at most, five over depending. I get better mileage and feel a lot safer. I now believe most people have no idea and drive like maniacs because they do not fully GROPE what they are doing. So often over the years some guy or gal is in such a hurry she is endangering everybody else and driving waay too fast and recklessly and yet, after a while, I am right beside her (oh shit I am getting sexist the guys do it too) at the red light.

Car or van full of her family, children she will do anything to protect and yet she thinks she is safe in her big ol' SUV or van and yet she does not understand the physics and bitches at her husband about gas prices and yet he drives just as fast and recklessly.

I keep hoping for the miracle of automotive understanding but nah... it will never happen and they will just keep on bitching about gas prices and keep right on driving as though they were playing a video game. I often think they think they are.

Just a few thoughts.

Steed

[vakkotaur.livejournal.com]

Ethanol vs. straight gasoline is certainly a factor and probably the major factor in things here. I drove Jay's RX300 back from Detroit this past Monday and got significantly better mileage than I would get with Minnesota's 10% ethanol gasoline (mid 20s instead of high teens/low 20s). Driving highway miles also helps. And if the weather wasn't too hot or two cold then the two big possible power draws (rear window electric defroster and air conditioner) aren't there. My Corolla is rated 38 mpg highway and I can get just over 42 mpg highway with straight gas and ideal conditions. If any significant the wind was with you, that can also help more than many suspect. With "E10" I'm lucky to get 38 under ideal conditions.

Octane is meaningless for simple efficiency.* Octane rating is about engine knock, not power. Ethanol boosts octane rating, but decreases power. To get the same 'bang' as a gallon of gasoline would require something like 1.4 gallons of ethanol. (This means that while E85 is slightly cheaper than other stuff, it's a lousy deal in terms of cents per mile.) In places where ethanol is not outright mandated for everything, it's not unusual to see cheaper 89 octane with ethanol and more expensive 87 octane without it. In terms of cents per mile only, the 87 octane is the better deal.

* High-octane is used in engines that can deliver more power, but this is because they run at higher compression and can get more power out of the fuel. The higher compression makes the engine more likely to knock (premature detonation of the fuel) and so the higher octane fuel (which is less likely to detonate early) is required.

[altivo.livejournal.com]

That all makes sense. I am very conservative about the air conditioning and rear defroster anyway, but neither was used this trip. I probably had a headwind rather than a tailwind, but it wasn't that significant. I normally get about 24 mpg on Illinois fuel doing highway driving, so 29.8 is still exceptionally good. And that was on a fuel mix of half Illinois and half Michigan fuel. So if Michigan had no ethanol in it (I didn't look) and we know the Illinois fuel had 10%, I was running on about 5% ethanol. Sounds like I'd be breaking 30 mpg if I lived in Michigan. That's darned impressive for a nine year old Cherokee.

[vakkotaur.livejournal.com]

* Vakko re-reads what he wrote and oogs. Evidently he really needed that nap and probably should have been drinking more water sooner, too. At least the meaning is right, even if the execution was... decidedly non-ideal. "Two cold"? Erf. And that's just one screw-up.

[ducktapeddonkey.livejournal.com]

When I used to ride my old bike an hour and a half each way to college, I really got a lesson in just how much difference fuel makes in an engine.

I used to think I'd get better mileage from higher octane (more expensive) fuel.

Turns out I didn't. In fact at about 70mph, my rpm dropped by about 250-300 when I was running the cheaper stuff.

Whatever the cause though, 30mpg is great for a nine year old vehicle of that size. Is it four wheel drive?

[altivo.livejournal.com]

Yup, it has 4WD though I seldom use that, certainly not on this trip. It has been handy in heavy snow though. I'm sure I wouldn't get that kind of mileage with the 4WD active.

[cabcat.livejournal.com]

It isn't unusual to get really good economy on long highway trips, as opposed to urban driving. The Otto cycle engine (piston engine) uses the most petrol upon accelleration.

My little Charade returns 6L/100kms or 40mpg and I have the hammer down most of the time. Also it has been slightly modified, and runs on wider wheels and rubber now. But Its still pretty good and the car was made 21years ago :)

The only way to check your fuel economy properly is to fill right up to the first click, reset your trip meter, drive around. Then when its next time to fill up, fill up to the first click note how many litres (gallons) you put in and the mileage on the trip meter. That is the only way to do it properly, going by fuel tank capacity is useless and the fuel gauge is even worse.

My little charade runs on the good stuff 98 octane (note: Australian petrol is rated at RON only...US petrol is rated at an average of RON & MON, hence ours will seem higher ;))

The day of the Kei Car and sub compact is here!! Its like 70's all over again. Did Ford, GM & Chrysler learn from the 70's? Nooooo!

[altivo.livejournal.com]

Actually Ford, GM, and Chrysler all learned from the 70s, but then they gradually made everything bigger and more powerful again because whatever they built with bigger engines and more space sold more vehicles. It's the American buying public that is at fault here. By the 90s they were demanding bigger and bigger cars, more and more like high powered trucks with luxury interiors. The SUV. So now they're unhappy that their big pigs only get 12 mpg. Well, maybe they'll vote some of these Republican fat cats out of office this time around, since all of them are getting rich off excess oil profits.

I track my mileage exactly as you describe, which is why I was so astonished at the sudden jump. Living in a rural area as I do, most of my trips are fairly long and at speed with few stops. And one reason I always get pretty good mileage is the fact that I don't go for jackrabbit starts but always accelerate gradually. I really dislike driving, and one of the things I detest about it most is being tossed around in the vehicle by fast starts and stops or sharp cornering. Precisely the stuff most people seem to love, I hate.

[cabcat.livejournal.com]

Oh I also seem to get the same economy on the standard 91octane and premium 95 octane. But better performance and smoothness on 98.

[cabcat.livejournal.com]

How long do people keep their cars in the US o.O
Here its not unusual to see cars 20 years + on the road still, or people keeping their cars for a fair bit longer than 5 years. (also we have far less choice in cars and people do tend to repair their cars rather than replace them)

Hell I can't afford to buy a car from 97 yet >.< but then cars tend to keep higher resale in oz and tend to be far more expensive to start with, even after conversion of currency.

[altivo.livejournal.com]

I don't have hard statistics on this, but from just observation, I'd say the typical USian keeps a new vehicle for four or five years before trading it. That applies to the portion of the population that would always buy new. Those who can't afford new cars and always buy used vary much more widely in how long they retain the same car.

Cars are status symbols and shiny toys here. There are many people who buy a new one every year, trading in the previous. Or every second year. The media is drenched continuously with automobile advertising, it's a constant brainwash thing. They make out that you're somehow a traitor and unAmerican if you don't buy new cars all the time, drive like a maniac, and devote all your spare time to washing and polishing.

I'm surprised to hear that vehicles are that expensive in Australia, relative to income. Are cars manufactured there at all? Or are they all imports? The price of a new car here is probably, on average, about half a year's income to many people. When you convert that to a four or five year loan payment, the monthly cost is about 20 or 25% of available spending money. Seems like a lot to me, but most people just HAVE to own a shiny new toy all the time so they bite the bullet and do it. Of course, the Republican yuppie elite have much higher incomes to waste, and it's less significant to them than to the average person.

Americans also do a huge amount of driving. They don't plan trips to minimize fuel use or wear and tear. They think nothing of driving for hours to spend 20 minutes visiting or shopping. My insurance companies have always been very suspicious of the mileage I report every year. They tell me it is only half of the national average. I get a slight reduction in my insurance costs because of that, but they are constantly checking up on me to make sure my behavior hasn't changed. At one time I averaged only five or six thousand miles a year. Now that I live where every trip is two or three times the distance it used to be (I used to drive only on weekends, because that was the only time I had to do it) my average is up to more like ten thousand a year. But that is still well below the national average.

Consequently, it is easier for me to keep the same vehicle for about twice as long as the typical owner would. I find that around eight or nine years, things start to wear and need replacement. The cost of maintenance is still less than the cost of a new car, but having to take the car to a mechanic for some nuisance thing every four to six weeks gets to be a drag and that's when I start shopping around for a replacement.

Oh, and one other thing I do differently. I don't usually make car payments. Instead I save money in a bank account so that I can pay cash for a vehicle and have no payments to make. It's planning ahead rather than paying for your sins after the fact. ;P And I guess it's very rare, too. But I pay no interest as a result. Instead I collect interest from the bank until the time comes to buy the car. I used to think paying cash was a good bargaining chip with the dealers, but it no longer seems to be so. They derive a good chunk of income from the interest on loans I guess, and I usually get a hard sell for a loan even when I tell them up front that I'm paying cash. I dislike car dealers and negotiating to buy anyway, another reason that I wait much longer between car purchases.