Bad gas mileage in new 08 Civic Si...

[Eddo]

I just bought a new 08 Civic Si in January. I'm only gettin around 320km to a full tank of premium. That is driving in the city with winter tires and it's cold out. I was just wondering if anyone who has an Si got bad gas mileage when the engine was still new? I have 2200km on the engine.

I took it into the honda dealer and they said it has no leaks in the tank, and I don't think that it is running rich because there is no black smoke coming out of the tail pipe. I don't drive it hard, only hitting the vtec a couple of times per week.

[slicknick]

winter gas is not as fuel efficient due to the ethenol (sp?) put in it, so it won't freeze easliy

[volvo9]

Do you let your car warm up for a while in the morning?

What kind of city driving, like around town or constant stop and go?

That's pretty bad but if you are driving constant stop and go and let your car idle for a long time in the morning I can see getting really bad mileage.

[twistedframe]

it has to do with the engine breaking in. Most people have reported bad gas mileage for the first 1000-5000 miles. Add that to the fact that its winter and you get really bad gas mileage. It should improve as you put more miles on your car.

[Eddo]

Yeah it can be pretty busy city driving sometimes. I would say its about 50% heavy traffic driving and 50% just normal city driving.

I usually let my car warm up for about 2 minutes before I start driving. It is pretty new so I wouldn't be suprised if it just needs to break in more. It still seems a little low though even for city driving and being new. Somewhere around 16mpg right now.

[CameronJr9]

Welcome to 8thCivic, Eddo. Like everyone else has said, give it some time. The conditions right now aren't great for good gas mileage. I drive an EX, and I've actually dipped below 30 mpg lately (which is unheard of). Warming your car in the morning, using "winter" gas, and your combination of moderate to heavy city driving will produce worse-than-desirable mpg...especially in a new car.

[saiaba]

Probably wont help... My first tank of gas.. from full to warning light I got 240 miles, mixed city and highway.
2nd 244 mixed driving
3rd 280 mixed
4th 305 mixed

Everytime filling up I put in like 10.1 gal.. so just guessing and not doing the math my avg gas mileage is like 25-26 mpg can't really complain, I only have about 1700 miles, so here is to hoping as it breaks in more it will get better.

one or two tanks inbetween where i got bad mileage but i was vtecing it a lot.

[Locwan]

Eddo, I got my Si Sedan in January this year, and it now has about 1700km on it. I'm in Toronto and the weather has been very cold here for the last 3 weeks. I saw my first tank getting 14L/100km!!... (driving mostly in the city like yourself, and very rarely gone above 4000rpm.

Although the economy slowly increased for the past couple of weeks, I'm still hovering around 11.5L/100km right now on a tank of premium.. so you're not alone.

I'm thinking along the same line as you right now; engine might not be fully run-in yet.. plus I've been told by mechanics (no proof though) that the first tank of engine oil from honda contains a small amount of abrasive materials and is thicker than regular oil to aid the engine's break-in process and protection, which might account for some of the engine's lost in fuel economy, and peak power during this run-in period.

[Phalanx]

I bought mine in January as well... I do a mix of stop-n-go and highway driving... and i let the car warm up a little bit on cold mornings

I been getting between 23 and 27mpg thus far... depending on how hard i drive it and what the conditions are.

[MBK]

if you are not doing highway, and are doing city, and "real city" which is lights, stops and goes... then your gas mileage will be low. its like it for every car. unless you are crusing in the higher gears for the majority of your miles, you will not see that good gas mileage people are talking about. if you are hitting lights the majority of your driving, stopping and going, driving short distances, going up to speed then coming to a stop and doing it again... then you will not get good gas mileage; its like that for every car, unless its a hybrid.

[thephenom]

Winter usually uses more gas, my old civic, winter I get about 400km, summer I get about 470-500km.

With my Si with 2900km on it, I get about 400ish km per tank (~11L/100km), I have a mix of about 40% highway, 60% city. And my city driving isn't fully stop and go.

[Locwan]

I agree that winter and city driving will definitely use more gas. However, having a machine with more performance potentials under my right foot when I need it is a good enough reason for me to "endure" the less than ideal gas mileage.

That being said, it's always nice to make sure that when not I'm not under the fast bug's influence and putting pedal to the metal, that I am getting the most out of my expensive tank of premium.

Since most of my driving now is in the city on non-congested roads, I'm curious to know what the best rpm range is for the Si's engine when traveling at between 60 to 70km/h. Anyone have a scan gauge with info to share?

I've also noticed that honda's recommended shift points for the K20Z3 engine is around 4000rpm... (shifts at 27km/h,47km/h, 60km/h...) I wonder if this is based on fuel economy.. having to rev to 4000rpm during leisure driving in the city seems a bit on the high side for me..

[thephenom]

Originally Posted by Locwan

I agree that winter and city driving will definitely use more gas. However, having a machine with more performance potentials under my right foot when I need it is a good enough reason for me to "endure" the less than ideal gas mileage.

That being said, it's always nice to make sure that when not I'm not under the fast bug's influence and putting pedal to the metal, that I am getting the most out of my expensive tank of premium.

Since most of my driving now is in the city on non-congested roads, I'm curious to know what the best rpm range is for the Si's engine when traveling at between 60 to 70km/h. Anyone have a scan gauge with info to share?

I've also noticed that honda's recommended shift points for the K20Z3 engine is around 4000rpm... (shifts at 27km/h,47km/h, 60km/h...) I wonder if this is based on fuel economy.. having to rev to 4000rpm during leisure driving in the city seems a bit on the high side for me..

For cruising, stay around 2.5k rpm. I usually shift at anywhere between 2.5-3.5k.

[Eddo]

Right now I'm shifting around 3500rpm, and I usually try to keep steady driving around 2500rpm. At 60-70km/hour and normal, non-congested driving, this would put you in fifth gear.

It's a very high revving car so I can see Honda saying that 4000rpm is the best shift range, but I agree with you that it is getting on the high side.

[shutter13]

winter + new engine = shitty mileage

you'll see it start going up in the spring

[TommyD]

Shift at 4k. I know these engines pretty well. The Si engine is my 11th Honda engine. One V4, one Vtwin, one V6, and 8 inline 4 motors. Shift at 4000-4500 RPMs. When cruising, whether on a city street or highway, maintain a constant speed. If you are constantly accelerating and decelerating your mileage isn't going to be good. What the others said about winter mix fuel is correct as well. If I did the conversion right you are averaging 20MPG. If you are doing 50% heavy traffic and 50% city that is the mileage you are going to get. It's also not worth the time to constantly short shift as it can bog the engine down.