Hi guys,

So I've been searching and haven't really found any conclusive threads on everything that can be done to increase fuel economy on our cars.

From my previous car experience, and also being an engineer myself, I have had good results leaning out fuel mixtures when having my cars tuned, as well as removing catalytic converters and replacing them with "test pipes" (also leans out fuel mixture as engine can breathe better).

So I'm curious what people have done to their cars that has resulted in better fuel economy.

I currently get 19-20 city, 27-30hwy, and 23-24 combined:

Oh btw, my car has 3 years left before its paid off, and I've done analysis vs buying say a 2009 VW Jetta 2.0 TDI that gets 45mpg hwy after minor mods, but the jetta would still be costlier over the next 5 years which is how long I plan on keeping the car.

I already have K&N Drop in filters,
I use Chevron w/ techron fuel system cleaner regularly.
Check tire pressure regularly, I run a few psi over door at 35psi when hot.
I drive as gingerly as much as possible.

Things I am contemplating doing:
-Sending my ecu to Eurocharged for a tune, they claim 2-3mpg increase.
- Replace the fuel filter, at 81k now.
-Removing all catalytic converters, not resonators, and replacing with reversible test pipes. I'd use double "spark plug" de-foulers as a cel fix (moves the oxygen sensor out of the flow of the exhaust so it cannot detect the additional carbon in the flow)
- OBX "Kleemen" copy headers - I've used obx on different cars previously and had good results
-Removing spare tires and other stuff from trunk... I have AAA Platinum anyway.
-Maybe switching to lightweight wheels like Enkei pf01's (18.2lbs) has to be a reduction from the stock c230ss 17" wheels. I'll weigh to confirm.
-Switch to Continental DW tires from my current Kuhmo's - 14lbs savings for the set!
- H&R Springs - reduces drag coefficient, really by a negligible amount, but it'll help the mod part (see below)
Any other realistic mods/ changes I could do? I live in Florida so not running the AC is out of the question.

Thanks in advance for the suggestions.

P.s. This will also help satisfy the mod bug that I've been suffering from recently... this is the only car I've owned that is still basically... stock.

James

 

Ok, I don't know how else to say this, but you are going to spend how much to save how much? I am just wondering if you are getting to the point of diminishing returns. If you want to mod your car because you like the looks, ok, and that is what you want to do to your car. But if you are getting new tires, rims, etc. to save 1-2 mpg and I don't know how much it will really save if anything, I am wondering on the cost vs benefit and if there is one. I don't want to say don't mod your car, because I have seen some cool looking ones! But if all you are looking at is better gas mileage which the subject of the post is, is it worth it?

 

Hi marcanders,

Totally understandable response, and I feel the same way.

I may not do all of these things because of just what you said, point of diminishing returns: You also hit it on the head that I have an urge to mod as well.

Point of this post is really to ask others if they have done anything else additional that's helped with mileage. I listed the things I did so I don't get the same old, "change your driving style, remove weight from the car, buy a more economic car" responses.

For sure I'm going to get my ecu tuned, replace my fuel filter, remove excess weight from the trunk, and change to lighter tires when these wear out. I've consulted Jeff at eurocharged for his opinion on removing the cats. If I do that I'm capable of fabricating the front section from headers to Y pipe myself for less than $100 in 304 stainless, so no major investment there.

Thanks for the response

James

 

Is there a point to all of this, last time I was in FLA (Apr/May) gas is so cheap down there compared to what we pay and the rest of the world. I pay for 91 octane $1.47/L or $5.56/us gal

Cheapest way to get better fuel economy is to drive on the highway with the windows closed and AC off at 58mph with cruise, and treat the gas pedal if it has an egg between it and your foot. Running skinnier tires also help

And while you think that the MB Bluetec is great on fuel and hence the "savings" price out what the Ad-Blue urea costs and the savings are virtually nil, not to mention the service costs for the Bluetec engine

In other words, there is no such thing as a free lunch

 

Hi Boom,

Yes there's a point, its to see if anyone on here has any more suggestions on how to improve the fuel economy in our little car.

The comparison on your part of the world's local gas prices compared to the relatively cheap prices in Florida is kind of irrelevant isn't it? I mean, I'm English, so anytime I visit there I see they're paying £1.10/L which is about $8/US Gal. Doesn't affect me living in Florida.

Thanks for the suggestions. Running without ac though here, will cause the aforementioned egg under my pedal, to be poached, so I won't have to worry about breaking it then! Lol

 

How much of a fuel savings do you get by removing the cats? I live in a state where I have to go through a car inspection every other year, so putting them on and pulling them off every time i go for inspection would drive me nuts and would want it to be worth it. But of course that is where I live.

 

^ there's ways around that lol. But there's no emissions inspections here in Florida.

I couldn't give you a definitive number unless I did some real world flow testing and monitored air fuel ratios, however it would be marginal. Maybe 1mpg at best, but you would also free up probably 5hp on these cars since we have 4 of them.

 

I hear ya in the ways around it. I guess I am lazy and wouldn't look at taking on and off. When your tires run out, you can look at replacing with more fuel efficient ones that are skinnier, but would the cost benefit of rims be worth it? Hey, people buy new shoes for their car for looks and is totally justifiable if that is what they want to spend their money on, just don't kid yourself on why you are doing it.

Oh... The poached egg comment was funny!

 

Other than driving habits most of the tricks in getting the engine to perform at the peak while delivering fuel economy has already been done by the engineers at the factory. It is a balancing act to find the best compromise between power and effeciency. More power = more fuel; better fuel mileage = less power.

I would be happy just to get the advertised MPG or L/100km that the manufacturer or EPA or Transport Canada says that the car will get.

BTW £1.10/L is about $6.43/US gal (3.78L/ US gal)

 

Agreed on the rims. It's kind of a dual benefit.
But decreasing rotational un-spring mass has a huge effect on other things as well, like braking, handling and acceleration.

I weighed my stock wheels & tires this morning and they came in at 46lbs front and 47lbs rear. The enkei & continental tire combo saves 8lbs for each front and 9lbs in the rear. That's 34lbs of total unspiring rotational weight... That's actually quite a lot. Is it enough to see even a 1mpg gain.... Doubtfully, but the dramatic increase in other benefits, including aesthetics, might tempt me to do it.

 

While you may be correct about the currency conversion, (I was just generalizing), more power equalling less fuel economy is totally inaccurate.

By rule of thumb? Sure, I'd agree, but trust me there's engineering and design techniques that can be taken into account which will net better fuel economy while still having higher power. For the power this car makes it leaves a lot to be desired.

For example, my supercharged Honda s2000 makes about 450hp at the crank being conservative, and averages 22mpg still.

Higher compression, cylinder dome shape, lift n duration on the cam lobes, ignition timing, exhaust scavenging, intake and exhaust port sizes, air fuel ratios, rpm vs hp., etc etc

Car manufactures have governments, rules regulations and emissions standards they have to comply with. All of this hinders them from reaching their full potential.

 

it is true that emissions standards don't allow the full potential of the engine but there is one other factor that I did not include and that is reliability. Sure you can get tons of power out of any engine but at what costs? F1 engines get 800+hp out of 2.6L but they only last about 500km (2-3 races), while the power output of your S2000 is impressive I wonder about the long term durability of the motor and other components as they were never designed with that power in mind.

more power can be had with an aggressive cam but at its expense is a lumpy rough idling engine that most consumers would not put up with and hence the invention of variable valve timing

The M272 2.5L V6 does have power and a torque curve that leaves a lot to be desired, a lazy underachiever, and while my M271 has similar numbers 189hp/192lb ft it is 150lb lighter but getting that out of 1.8L which in its day was a very good Hp/L number and still delivering respectable torque (S2000 produced 240hp but only 153 torque)

Problem is that smaller forced induction engines can produce a lot of power and get great fuel economy if not pushed but drive a high output engine as if it has that power all the time and you will find that you get an mpg similar to an engine twice its size

 

Agh we agree again!

I have a friend that has the same setup on his s2k with over 100k miles on that setup. Still purrs like a kitten.

All I'm really saying is by today's standards a lot more could be done and still be reliable. Leaning out a/f ratios conservative to moderately in the non wide open throttle section of the fuel map will make a noticeable difference, while still being just as reliable. Obviously getting too aggressive will degrade reliability due to the hotter running engine etc.

In hindsight I kind if wish I bought an 05 I just couldn't find one with what I wanted when I was looking. But I didn't, soo suggestions to make the v6 more economical are welcome from anyone!

 

Get manual conversion?

100% stock Manual 6spd M271 (high comp, only 122 hp) C203 body.

5,8L / 100km (40mpg) on long-distance driving, lower on pure highway driving.
7,3L / 100km (33mpg) on average.

This is with the stock sport-package 245 tires in the back and 225 in front.

Edit: sorry didn't notice it was the V6.. Im blind

 

I yeah 272 motor 😰ive never seen 33mpg in my life

 

are you sure you have the M271 engine and not the M111. With 122hp I really feel for you, and I thought that my 189 is not enough

 

I suggest you convince MB USA to import diesel C Class CDI's.

Under 100km/hr I can achieve 4.7 l/100 km/ on a trip & never under 5.5 l/100 km ( 45mpg Imp) when travelling at 117km/hr with A/C on . The upgraded engine kills these figures.

Mine is a great little flexible engine with 125 KW & 4000 Nm of Torque.

 

I wish, I'd buy a 220cdi in a heart beat!!

 

These cars are rather heavy for their size and moderately powered. They will be a bit thirsty, that's just the reality. As long as you drive sensible and keep the car well maintained which is exactly what you're doing the 23-24MPG will be the norm.

You should go ahead with modding the car as you will still achieve your current fuel consumption but have extra power to boot though you might drive a bit more spirited from time to time.

 

Thanks khan,

I'll definitely be sending my ecu for a tune, removing the trunk stuff, replacing the fuel filter, and when my current Kuhmo tires wear out, switch to the Continnental DW's, which are an 18lb savings.

Ill report back the difference, hopefully I can break 25-26 as a combined average.

When its time for new tires, I'll decide at that point whether or not I'm going to buy the pf01's as I'd be getting 17's again and they'd work with the same tires that would go on my oem rims.

All the other stuff like removing cats etc would be done after much more thought...

 

If possible how about driving to work out of peak hour.

Do you have synchronised traffic lights ?

Take public transport more often !!

 

M271 alright - Chain needs to be done, and it has only gone 85.000km
(To be exact; M271.971)

122 hk/5.200 o/min
190 Nm/1.500 o/min
Factory numbers on Combined MPG's: 29

Think they only sold these in the northern europe (taxing hp, not torque), not much information to be found on them really