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hey guys,

i'm new to the forum here. its been really informative reading the previous posts about how to increase fuel economy.

i have a mercedes 1982 230E. i currently get about 13L/100km in the city and about 11L/100km on the freeway.

I have recently changed my air filter, distributor cap and rotor button <--- these 2 havent been changed since 1982.
In a few weeks i will have a major service perfomed on it... spark plugs, oil etc and tune

fuel filter, spark plugs leads, and probably oxygen sensor to be replaced <-- these havent been replaced since 1982.

I feel that i can push my fuel economy even further. I don't speed, and i don't accelerate and brake hard, and my car has always been serviced at recommended intervals. I follow all the fuel economy tips.
Is there anything else i can do to reduce my fuel usage?
Will the replacement of parts like the fuel filer, spark leads and oxygen sensor make any difference?

thanks

- Chris

Welcome to CleanMPG!

It sounds like you are off to a good start!

here's a bit more info on my driving.

i drive about 60% city and 40% freeway.
my recommended tyre pressure is 28psi at the front and 32psi for the rear. i currently have it inflated to 34psi at the front and 38psi at the rear.
also, my car requires the use of 98 octane (runs best on shell optimax here in australia). my merc specialist mechanic told me the use of shell 95 wouldnt do any harm to it. i have been running it for a period of 1.5 yrs now after the phase out of leaded petrol, and it hasnt blown up on me yet :)
i have tracked my fuel consumption over a period of time and here are the results...

LITRES PRICE/L TOTAL kms L/100km Fuel type
31.52 126.9 $40.00 193 13.91 SHELL 95
26.85 122.9 $33.00 193 13.54 SHELL 95
26.13 122.9 $32.10 200 10.61 SHELL 95
21.21 124.9 $26.50 179 10.06 SHELL 95
18.01 124.9 $22.50 160 19.56 SHELL 95
31.29 134.9 $42.20 204 8.36 SHELL 95
17.06 134.9 $23.00 204 15.33 OPTIMAX
31.27 127.9 $40.00 277 11.59 SHELL 95
23.90 133.9 $32.00 180 23.72 SHELL 95
7.59 131.9 $10.00 58 13.46 SHELL 95
21.39 131.9 $28.20 159 13.36 SHELL 95
21.24 133.9 $28.35 159 15.45 OPTIMAX
24.56 137.9 $33.85 207 15.09 SHELL 95
31.24 139.9 $43.70 207 16.65 SHELL 95
12.43 138.9 $17.25 220 6.96 SHELL 95
31.62 139.9 $44.25 230 5.99 OPTIMAX
38.38 139.9 $53.70 332 8.59 OPTIMAX

i have started to track the amount of cold and warm starts that i do every day, checking and recording the tyre pressure each fill up, and also the amount of kms for freeway driving and city driving that are done each week. so i can really see how the fuel economy is being affected.
I have also switched to running it on V-power exclusively(which now replaces optimax here in australia) for a few months to see if there is any real improvement in economy compared with the shell 95. I have already noticed smoother acceleration with the V-power, but still achieved the 13L/100km mark for the past two weeks.

we shall just have to wait and see.

observations, advice would be appreciated :)

- Chris

Hope you don't mind requoting but taking the liberty to express your fuel economy in US miles per gallon. It seems like your figures are respectable....

hey guys,

i'm new to the forum here. its been really informative reading the previous posts about how to increase fuel economy.

i have a mercedes 1982 230E. i currently get about 18mpg in the city and about 23.4mpg on the freeway.

I have recently changed my air filter, distributor cap and rotor button <--- these 2 havent been changed since 1982.
In a few weeks i will have a major service perfomed on it... spark plugs, oil etc and tune

fuel filter, spark plugs leads, and probably oxygen sensor to be replaced <-- these havent been replaced since 1982.

I feel that i can push my fuel economy even further. I don't speed, and i don't accelerate and brake hard, and my car has always been serviced at recommended intervals. I follow all the fuel economy tips.
Is there anything else i can do to reduce my fuel usage?
Will the replacement of parts like the fuel filer, spark leads and oxygen sensor make any difference?

thanks

- Chris

thanks for that.

i will be posting up my fuel economy tips soon :)

- Chris

Have you practiced timing the lights? Do they have stop lights in Australia? I've never been there so I don't know. Try to conserve momentum as much as possible. If there are lights try to time them so they turn green as you get to them. Also, if there are hills there try to keep steady pressure on the pedal and allow your speed to drop if necessary so you don't use gas going up it.

Also, have you read about pulse and glide? That technique will help a little if you can use it in your commute.

I try to time the lights as much as possible. Here in Australia we can see on most intersections the lights for the opposite direction e.g. left and right hand sides. Most of the time it will take 3 seconds for the lights at my direction to change to green after the left/right direction lights have changed to red.

I also try to accelerate before approaching a hill and then roll down the hill without pressing the accelerator.

I rarely let the engine idle for more than 30 seconds before i leave.

I also try to avoid speed humps and the most straightest distance to my destination.

- Chris

Sorry, i drive the straightest distance to my destination, i dont try to avoid it :D

How big are the hills? Is there a reason you need to accelerate? Would it be possible to just pretend the hill wasn't there and not react to hit by accelerating or trying to maintain speed? Is there a lot of traffic around.

Also, do you leave a nice buffer between you and the car in front of you so if he speeds up and slows down or turns you can continue without having to brake?

Sorry guys,

It appears my fuel filter has been replaced twice (I am the 3rd owner)

in 1987 at 61,504km
in 1989 at 92,150km

Here are my owner's manual specs

Automatic transmission 4 cylinder 2.3L

city: 12.8L/100km or 22.1 mp impgal

at 90km/h / 56mph: 8.7L/100km or 32.5 mp impgal

at 120km/h / 75mph: 10.9L/100km or 25.9 mp imgal

there are not many hills in my area, well, not many that i drive on anyway.

i accellerate before the hill so as let the car move smoothly up the hill rather than labouring trying to get up it.

the hills that i do drive on (2-3) are fairly steep and my car just struggles if i try to maintain the same speed before the hill and labouring up it rather than accelerating and driving smoothly up the hill.

the traffic is fairly moderate around my area, most of the time it flows smoothly. i avoid peak times as much as possible.

i leave plenty of space between me and the car in front of me so i dont have to brake all the time.
i try my best to drive smoothly with minimal braking and stops.

Hi Merc230:

___Besides pressing up your tires to max sidewall, and changing her fluids with synthetic Mobil1 (weight appropriate of course), you can do a lot of things with technique. To begin with, DWL (Driving w/ Load) is what Tom was referring to. You do not want to accelerate at all but leave the engines load constant as you climb and fall over small hills, overpasses and the like. You drive by the engine load, not the speedometer or accelerating with your accelerator pedal. The basic setup and a few basic techniques should get you started for a nice increase.

___Do you have an i and aFCD (instantaneous and averaging Fuel Consumption Display) in the car? I see you have your tanks down but some of the other numbers posted sound like you have some FCD’s installed as well? If so, use them to tell you how you are doing at any given instant or over a segment.

___Is the 230 a stick or Auto? If it is a stick, you can do a lot more with her then you would have ever imagined and 40 mpg’s would not be out of the question depending on your commute and patience.

___Have you read any of the articles to the right side of the home page? Read the first 4 as they will get you moving forward quickly. Even though they all appear hybrid specific, the EPA article is really for non-hybrid’s and with a little training and practice, you will have that Merc punching through 25 and possibly even 30 mpg’s in no time.

___Good Luck

___Wayne

Hi wayne,

Currently my psi is set to 34 at the front, and 38 at the rear. The ride is much harder than the normal manual specs. I don't think i could go any higher without the beauty riding like a tractor!

So you mean by driving with load as hearing the engine as youre going up the hill to see if it struggles or not? I'm confused with this part. Or just keep the acceleration constant over small hills, but accelerate before going up steep hills?

The 230 is an auto. I was also wondering whether putting it into neutral would save petrol. However, when i do shift into neutral the revs are considerably higher. I dont have a (is it tacometer?) on my car to tell me how many revs i'm doing.
Also, the second gear helps the car up steep hills. I was wondering whether this would help me with my economy on the freeway, however the speedo states that second gear (but im not sure if i got this right) is limited to about 80km/h.

I also don't have the fuel consumption display. If only it did like my mum's bmw, i'd be leaving those manual consumption averages in the dust!

I'll take a look at the articles. I'll really fine tune the data this week in terms of driving and see what turns out.

Thanks

these are the parts that i have changed recently

- oil
- air filter
- spark plugs
- distributor cap
- rotor button

these are the parts that need doing * and the parts i consider doing ^

oil filter *
fuel filter ^
oxygen sensor ^
spark plug leads *
transmission fluid ^
power steering fluid ^
radiator coolant ^
getting muffler looked at *
checking out gaskets *

Anything else i need to look at?

i'll get a major service done on it as i will be traveling 600km early next yr for a holiday.
hopefully when everything is replaced and all the fluids are new and its running at optimum timing the fuel consumption will come down.

Hi Merc230E:

___If your Mercedes is riding like a rock at 34/38, another 10 #’s isn’t going to hurt matters ;)

___DWL is like riding a roller coaster. Your ICE doesn’t even know you are climbing a hill. I wish I could show you with an iFCD but for a non FCD equipped auto, all you need to do is lock the accelerator pedal in while climbing so that you slow down a touch and leave it there on the back side of the hill so you speed back up to your previous speed. Your cars speed will act like a rollercoaster. As it climbs, it slows. As it falls, it speeds up. The engine should not change load although it will change RPM a tad.

___As for the tune up HW, that is always a good thing. Replacing parts and using high octane fuels should only be mandatory if it is a maintenance item and/or parts are worn/dirty/broken. If you are replacing them for the heck of it, you may be throwing good money after bad. Have a good mechanic check it over but plugs, air filter, low kinematic viscosity oil’s, and the tune-up will get you to a FE baseline. Once we have that baseline, we can both start working on increasing your FE by numbers you would not have imagined if you are willing.

___I really need you to read the 4 or so top articles so you have a better understanding of the how’s and why’s you can achieve better FE then your car is rated for. Once you have an idea as to the way higher fuel economy is achieved, we can do a case study on your daily grind and see where we can squeeze out a lot more of those hidden mpg’s :)

___Good Luck

___Wayne

Hi Merc:

The one thing I didn't see mentioned is wheel alignment.
Has it been checked recently?
I have read that some people even go as far as getting the alignment done with the driver in the seat.

And I thought we were fanatics ;)

hello,

i had changed wheels and had them aligned and balanced about 1.5 yrs ago.

i am organising to get it done again before the trip next february. i'll probably get it done after the major service.

anything else?

- Chris

changed tyres sorry, wheels are originals...

:)

now i'm really stumped.

to calculate fuel economy is it

diving the kms travelled for one trip by the number of litres used for that trip, or do we use the kms travelled for the previous trip?

shouldn't it be calculated using the data from the same trip?

Please show how to calculate:

Litres Kms travelled

51.17 388
53.39 382.4
42.12 334.5
29.88 209.0


Thanks

I think you have it right. I'll try to explain it differently just in case.

Each time you fill your tank, you want to fill it to the same level. (Usually to the first 'click', others do it differently. It's not a perfect science but it works over the long run.) You also want to reset your trip odometer when you fill. So the next time you fill your tank you are only replacing the fuel that you burned since the previous fill up, and the trip odometer tells you how far you went. So the number of litres on your gas receipt aren't a direct measurement of what you used, but it should be very close unless there was something wrong with the pump.

As for the math, I don't understand metric FE numbers but if you want L/100km it would look like this:

51.17L/3.88(100km)=13.19 l/100km
53.29/3.824 = xx
42.12/3.345 = xx
29.88/2.090 = xx (too lazy to do the rest of them)

Does that make sense or did I confuse you more?

it is distance driven divided by fuel used for miles per gallon.

for L per 100km it is liters used for 100km.

The measurements are taken from a starting point to an end point
starting point could be begining of the tank, or it could be begining of a trip, or what ever you want it to be.

End point is the end of a tank, end of a trip, or whatever you want it to be.

what we have to do with your numbers is:

this number / (this number /100) =
51.17 / (388/100) = 13.188144 l/100km = 17.835306 MPGus
53.39 / (382.4/100) = 13.96182 l/100km = 16.8469859 MPGus
42.12 / (334.5/100) = 12.591928 l/100km = 18.6797911 MPGus
29.88 / (209.0/100) = 14.296651 l/100km = 16.4524254 MPGus

Hi Merc230:

___You always use the miles or km traveled and the amount filled at the pump from your last fill up to your current fill up. Once you have the amount and distance, you can calculate and or display your FE whichever way you please. Here in the US, we would convert the km to miles and divide by the liters converted to US gallons. In Asia, they appear to like km/l so you only need to divide each tanks km traveled by l filled. In Europe, they like both the Imperial mpg (miles divided by an imperial gallon) as well as l/100 km.

___Most use what is standard in their locale. We have some Canadian’s here that like to post their FE in l/100 km which suits their standards perfectly.

As an edit, you guys are too fast!

___Good Luck

___Wayne

makes sense now,

although some ppl on the net calculate it using the litres filled up and the kms travelled on the previous trip, not the kms travelled on the same tank, which would throw the economy calculation out the window.

Hi Merc230E:

___Whoever pointed you to that is way off. Your FE is based on your current distance traveled to the point you fill and the amount of fuel you had to fill to bring you back to full. I top off so my tank data is accurate to within a 100th of an mpg but many cannot do this or will not due to possible issues with their Evap HW.

___Good Luck

___Wayne

everyone says to increase tyre pressures above the normal manufacturing specs for the car, or as some ppl above the figures on the tyre sidewall.

but just how much of an increase is too much? would you pump them up so high so as to save fuel, but in the long run significantly impacting on the tyre wear and handling of the car?

for example, lets take my merc...

owner's manual says 28psi at the front and 32 for the rear
my pirelli tyre sidewalls says max 44 psi

i currently have it at 34psi at the front and 38 at the rear. havent noticed any wear in the centre from the over inflation.

would evening out the tyre pressures to be the same all around make any difference, say to 36 psi or even 38?

finding the right balance for extra fuel economy, reduced tyre wear, and good handling is tricky to master.

please post your opinions...

thanks

A lot of us go higher, sometimes much higher than even max sidewall pressure with no ill effects.

The higher the pressure the harsher the ride. Handling will get better, wet road traction will improve, FE will improve. After a certain point the FE improvement gets less and less. This is why we aren't running 100psi. There is a point where the FE improvement pretty much levels out otherwise some people would be going even higher with the psi.

Snow and sand are the only times you don't want high pressure.

merc

Ive been running max side wall psi for years. Or a mix.

For instance:

Ranger PU. I run max sidewall front and rear of 35 psi. These are cheap Douglas tires. Last set lasted 57k miles or so.

Honda Accord. I run max sidewall front and rear of 44 psi. This are Michelin's MX series something. They make a ton of diff. tires. They have 40k miles on them and are wearing nice and even. I expect 50k miles out of them. If I want the car to handle a bit better I drop the rears to 40/42 psi. This helps to keep the rear end planted better when going over expansion joint on a free way clover leaf. Or any other harder than normal cornering where the pavement gets uneven or say big asphalt patches in the apex of the corner. The Accord doesn't get driven hard very much. The the automatic transmission just ruins any true fun that can be had behind the wheel. :(

Honda Civic. I'm currently running 50 psi front and rear with a sidewall max psi of 44 psi. The tires have 27k miles on them and look very good indeed. Nice even wear. I do drop them to 40 psi front, 38 psi rear if I'm going to have some fun behind the wheel say in eastern Oklahoma or western Arkansas. With high tire psi the Civic can get skittish. And skittish isn't needed when corner carving two lane hill county hwy's.

Another plus for higher tire psi in the Honda's is the reduction in road noise. Honda's are well known to have excessive road noise by design. Raising the pressure cut's about half this annoyance out. The ride is firmer! This doesn't bother the wife and I at all. If we wanted a cush plush ride. We would have bought Yota's or a Buick.

Over all pressing up the tire pressure to max sidewall will increase mpg. Amounts vary between, cars, tires and driving habits. In some case's like my Honda's it helps with road noise. In almost all case's it will make for a firmer ride and a tad better steering response. Draw back is,,, the car could get a bit light under foot and want to be a bit more skittish.

In the old days. ( look at that,,, old days ) when bias ply tires ruled the roost over inflation would wear the inside of the tire. Sometimes very quickly. Our steel belted radials with the low sidewall profiles help a lot with this problem.

I wont press up the tires on my truck above max sidewall because they have a much taller profile. Thus causing the balloon effect. The sidewalls balloon out causing the edge of the steel belt to roll up. Thus causing center wear. The lower profile on the Honda's tires makes the sidewall much firmer.

Under inflation will kill your mpg as well as the tires. The center of the tire will not wear as fast. The edges will wear terrible fast. Also more heat will be introduced to the tire at its weakest point. That being the transition point of thread and bottom of sidewall. This can lead to premature belt failure and separation.

There isn't much info on the net about over inflation. Under inflation yes. Car manufactures suggest psi rates at which they feel best compliments the car. Not the best handling, mpg, or longevity of said tire or car.

Tire manufactures put a sidewall max psi with load range on the tire and go about there way.

Tire retailers aren't going to comment on higher psi than car manufacturers recommend because they want to sell you more tires. They aren't going to say. "Hey try raising the psi a bit to help with the road noise. " No they are going to say. " try this tire, it runs a bit more quite " Or, I want better mpg. " Well try these RE92's." Not " Your EL400's have a max sidewall of 44 psi. Give that a go."

Everybody in my family runs max sidewall psi or darn close to it. And have done so for many years. :D

psy