new member 02 merc c230 kompressor

[kompressor]

Hi just stumbled upon you guys site while checking out some prius mods as I am looking to get into something more fuel efficient. but now ive been lurking for the past 3 hours or so and learning lots. the aero mods are inspiring makes me wonder if my 02 c230 might be a good candidate for mods. my best mileage in the c230 was 38mpg. its a 6 speed manual and its the hatchback.



this is a picture of it at the track with some low budget aero

anyhow looking over the site got me to thinking the car is not half bad already aerodynamically, it already has a plastic underbelly pan, small gaps at the wheels, and a good rear end shape. I am wondering now if maybe some grill inserts might be in order.

anyhow great site I hope to learn a lot.

[Red]

38 MPG is a nice number out of a super charged 4 popper. Welcome to EM

[kompressor]

that was best ever and some neutral down some hills over a 51 mile commute home, average highway is around 33mpg, average mixed driving is 27mpg, city is like 23mpg estimated , I've never done a full trip just city I always have some city and some highway mostly highway though. and i do see tons of stop and go grid locked traffic.

[kompressor]

I am a big greenhorn now so forgive me if i ask a question thats been asked a million times. but I noticed something while checking out the site the mention of the tires and fuel economy. the wheels on my car in that picture are not the stock wheels. I only use those at the track they are SSR wheels tire sizes 255/40/17 rear, and 235/40/17 front. I have 2 other oem sets of wheels for it one 16 inch and another oem set 17 inch, i normally use the oem 17 inch wheels with 225/40/17 tires. though i also have the 16 inch wheels which i use for snow tires on the car which have 225/50/16 tires.

the big wheels the SSR's cost me 3 mpg so I don't use them on the street. My question is between the remaining to sets of wheels would the 16 or 17 inch size make any difference at all in fuel economy, or just tire width ? also would it be advisable to go to a smaller tire width say a 205, or 195 instead of the stock 225 tire width ?

[tasdrouille]

Welcome to EM! Nice car, but I like the volvo better

[Daox]

Hello and welcome to EM.

The wider a tire is the worse FE you'll get, also the heavier the wheel/tire is the worse FE. You'd have to weigh your setups to see which is lighter and thinner.

I have the same supercharger from your car in my Tercel.

[MetroMPG]

Welcome. Yes, a partial grille block will help a bit. Merc is using them on some of its latest models. (E Class, C class efficiency series).

A variable one would be best for your case, since you do a wide variety of driving. One with manually adjustable operation might be OK in your case, since I suspect you pay attention to your vehicle/driving.

Your tire question is difficult to answer because one tire may have better built in rolling resistance than the other. But all else being equal... what Daox said.

[kompressor]

the wider wheels the SSR's. are the lightest of the bunch at 15.5 pounds but the wide tires do cost me 3mpg

[cfg83]

kompressor -

Welcome to EM! I always thought your merc was the "MB CRX", even down to the vertical mini rear window. I'm glad it looks to be a good MPG platform.

CarloSW2

[Daox]

The tire width is more of an aerodynamic issue (however its also a weight issue) so it is effected more at highway speeds. The weight is more of an acceleration issue so you'll see weight effects city driving more.