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And when buying an old car you really does not have a way testing how good is this particular car on mpg. It might require some money spent to get to the desired target mpg values - if it costs couple hundreds to replace sensors or make some tuning up than it again defeats the purpose of saving these 5-10 bucks a month which the mileage improvement can save you. Tricky subject... :-)

Also - with an old car, a single expensive unexpected repair can kill all your pre-calculated "profits" you expect, so choosing right car is extra tricky and is more in the hands of luck/fate.

It depends on the car...

That depends on you. I average, over the past 10 years, about 20000 miles per year...

So, let's say 20000/30 = 667 gallons, 20000/35 = 571 Gallons. Difference is 96 Gallons. 96*5 = $480 per year, or $40/month.

It's not all about money. Some people also feel a responsibility to conserve resources (clearly I am not one, since my car isn't nearly that good on fuel)...

Not necessarily. Only if that is your criteria...

Even $40/month is a substancial savings for some folks...

Am I?

The goal is the same and has never moved: to get the car which will cost the least amount of money it is ever possible. High expected mpg is only one of many parts to the main equation.

Some people forget about it and are so hypnotized with mpg that they are ready to pay more money for a car with not much higher mpg, so not justify the price increase. At some point they pay more for the car than they are able to save on gas money and in the process they sacrifice car performance and the joy of driving a nice car.

The same goes with improving the gas mileage on the car we own. If we can bump the mileage +5mpg but have to spend $500 to do it, is is worth it? I am afraid, not.

There was a guy here or some other newsgroup moding his honda or nissan to get the extreme gas mileage - he has removed from his car EVERYTHING beside his driver sit, including spare wheel. Don't you think this is crazy? :-) One flat tire and towing would kill all his gas savings...

So it is good to keep in touch with the bigger picture to not get lost in the blind higher gas mileage chase... :-)

"Pszemol" wrote

I did not pay a $1000 more.

Of course! You are correct - all depends on your particular car and you kind of driving - I gave just two simple examples ilustrating how simple the math really is - it is good to realize how much you are really saving on a car with higher gas mileage because the math is really simple and most of folks out there imagine the savings to be enourmous when switching from a car which makes 35 to a hybrid and drive only 10-12k miles a year. Just do the math and make an educated decision without guessing or wrongly assuming huge savings...

Similar math you can do to justify buying a foreign car requiring premium gas. Premium from regular is usually only 20-30 cents apart per gallon so it is relativelly easy to calculate how much more or less you will spend on gas buying this passat GTX, or audi A6 or you rather stay with honda accord which is perfectly ok consuming regular unleaded. :-)

More than what?

I was not talking about you but in general about car choosing process.

You look at the one car (civic 91 with 27 mpg city) and another (civic 93 with 29 mpg city) and you know that maximum you can save in IDEAL, LABOLATORY conditions is 2mpg. How much these savings are worth to you it depends on how much miles you make per year... That's all.

And this mileage applies to new cars - cars with high mileage will require a lot of work to reach that original, factory levels. So for used cars I do not think comparison of factory values makes any sense at all in terms of comarison. You can probably find out there 91 civic which burns much less fuel than a random 93 civic.

How much fuel will your burn? You will see, soon... I wish you good luck!

I was talking about a year old car, not a twenty old junker.

I know :-) You were talknig about one year old... :-))) But we were talking here in this thread about the sense in making mpg comparisons when buying almost 20 years old junker (93 civic).

"Pszemol" wrote

Use the word "one" in place of "you," then.

Nonsense. My 91 Civic's mileage actually improved with age and is better than the EPA's stated values. I watch it like a hawk for the last five years, and it has not changed. You are not the least bit up to date on what old cars can do these days.

:-)

How can you explain old car with leaky cylinders and not perfect compression, dirty/worn out fuel injectors etc, etc, using up less fuel than when they were new?

How exactly do you measure your gas mileage and what is the mathematical error/uncertainity of this measurement?

"Pszemol" wrote

Engine rings do not fail nearly as soon as they used to, that's all. Without googling, I'd say technology has improved additives to gas and engine oil, along with engine materials, so engines last longer. You can google and find more on why engines last longer these days. Even American manufacturers' cars are lasting longer.

I have not read of fuel injector problems here, though people have replaced them without any change in performance. Tegger did a report a while back on what he saw when he replaced his fuel injectors. Google the archives.

Seems like the only time we read here of a Honda with poor compression is when the car has been driven hard. It's rare to hear of someone's engine giving out here, unless it's due to a failed timing belt.

Trip odometer set to zero at every fillup. Fill to one click. Divide miles by gallons. Average over many fillups, or a few.

MPG often falls off for many people simply due to poor basic maintenance habits like not changing out the plug wires, plugs, distributor cap, PCV valve, air filter, etc. Also, failing to use OEM for these parts (air filter excepted) can be detrimental to MPG, IMO.

I am not saying they last shorter, I am just saying they consume little more than when they were new and all was clean, matching perfectly and in order.

I simply cannot compute the argument that the car with 185 thousand miles on the odometer can consume less fuel than when it had - let's say - 10 thousand and everything else was brand new and in perfect adjustment.

This is very unreliable method and you have many sources of error factored to your calculations!

I see I am unable to convince you... that is ok, too :-)

"Pszemol" wrote

Then you are not acquainted with changes in technology. Just the use of unleaded fuel in the last 30 years has altered engine life dramatically.

Nonsense, but thank you for convincing me you are a bullshit artist.

Sure, and car after 200 thousand miles consumes less fuel than the same car when it was brand new... of course :-)

Here we go with name calling game... How mature is it? :-)

You simply do not realize where are the sources of BIG errors in your method. For example, starting at your shut-off nozzle, it will shut-off in very random place near the top of the tank. It will depend on the brand of the dispenser, velocity of the fuel in the hose (how strong is the submersible on the site) even the same nozzles will differ in the shut-off reaction time. Shut off time will even depend on how deep you put nozzle in... It will also depend on the particular fuel was delivered that day on the site you refuel... If the gasoline happens to be specially foamy that day, it may actuate the release mechanism in the nozzle prematurely, with the result that you end up with less than a full tank of gas. If you stop fueling in the middle and let the foam settle, then fuel to the top it will be different.

Mixing city and highway milleage is also a huge factor in error estimation. Ambient air temperature, weather condition (rain), holiday period and less cars on the road, less stops&go. Averaging can only help a little.

Well, good luck with your car! :-)

I'm offended!

What would he call my '82 'n '83 junkers? Scrap???

Grrrrr

JT

(Just pokin' along with my ol' 42mpg junker...)

but that doesn't make a damned bit of difference to an average!

no dude, the average /defines/ the whole exercise.

good luck with your math.

1. 2008 - 1993 = 15. see my earlier comment about your math.

1. you don't seem to understand that modern cars are much heavier than the older ones, and thus, because the extra weight takes more energy to move around, many modern cars lose their fuel efficiency advantage compared to older ones. or at least, older hondas. a literally 20 year old crx hf can out-perform the current civic hybrid by some margin in fuel economy ratings.

15 years old junker or 20 years old junker - what is really the difference?

I was never comparing her 93 to todays 2008 models but I was comparing her

93 now with 185k miles to *the same car* when young, with 10k miles in 1993. Do you really think her 93 with 185k burns less fuel than when it had 10k miles on the odometer? I certainly doubt it.

It does if you want to extract city mpg from highway mpg. If you take too much data into the average you will blurr the difference between city/highway mileage and for some cars it makes a huge difference.

It introduces some problems, too...