my failure story?

[ever_green]

I did not see a thread for failure stories so here is mine:
First of all if you want to skip a short background story skip to second paragraph
Few years ago (2008) i graduated from college and bought my first car (impreza). car was/is very nice with no problems and has gotten me home through the worst winter storms and plus have had lots of fun messing and modding it. throughout my ownership i fell in love with engines, transmissions, exhausts, pulleys, belts, flywheels and all the other nuts and bolts. so with this i started to really get into auto world by reading perhaps 400-500 articles so far on various car parts and auto techs. After i became an internet engineer, i started to actually use my hands: fluid changes, brakes, shock/struts, ECU flashing, diagnosing, engine builds (had a friend help) and various other works. I can say that my car is perhaps my biggest hobby after golf lol. anyway long story short, i recently focused on solving my horrendous fuel economy problem. i was only averaging 21mpg around town and about 17mpg in harsh winter conditions. My Father achieves the same numbers with a turbocharged engine making 70 more horses and carrying 1000lbs more weight. I thought the mods might have something to do with it but it turned out it was NOT the modes. It's the car and maybe the way i drive?

So i came here and studied the 100 or whatever number of ways to improve fuel efficiency. my numbers started to improve but only slightly so and i was NOT really paying less at the pump with oil prices on the rise. Not satisfied i looked for more hardcore methods to improve my numbers. Then I came across a brake specific fuel consumption thread on this website and for the past 6 months (and i really mean 6 months) i really got in to it. i read almost every page on BSFC on the net and tried various methods (by looking at a subaru bsfc chart) to improve my mpg during pulse or acceleration. The change was instead of being easy on the throttle i was slightly more aggressive to accelerate (+80% load at 1500rpm-3000rpm vs 55-60% at 2500rpm). This did not help. in fact i learned from my log that accelerating at low rpms with high load was the culprit in my 'bad days'. I even tried an experiment and actually posted the results here and it proved to me that the lower the load, the better my fuel consumption. This is despite the fact that my car doesn't enrich mixture or go open loop unless above 4000rpm.

Anyway i have failed with BSFC and the gain from other tips such as engine off coasting or off at red lights have been too little to be worth the trouble. The only significant gain was maximizing coasting coupled with drive in lane with least resistance. Drafting was also great but i stopped doing that for safety reasons and my UEL headers scared/concerned lotta truck drivers. One of them actually pulled over once probably thinking that the noise was from his truck haha. i think i will go back to driving my car the way i used to

[2000neon]

Hey, sometimes it can be discouraging. I encourage you stay with it and keep trying, you are certainly on the right track. I see you're from Toronto,.so I'm sure you've been getting this cold (-15 to -20*C) weather too, and just the general cold temps from winter. Temperature has a huge effect of fuel economy, so since you joined in May, and your MPG has stayed the same, you have probably improved about the same amount as the weather is bringing you down. I remember seeing Diesel dave post something like every 1 degree Celcius equals about 1% in fuel efficiency. Starting from may in 20*C weather, to today in -10*C, if your mileage has stayed the same, thats about 30% loss in MPG give or take, and your improvements have almost completely cancelled that out!

I have the same thing with my car right now, my mileage is slightly dropping even though I am trying harder and harder to get the best fuel economy, however as soon as the temperatures start to warm up and we lose this snow, I'm confident that my fuel log will show my efforts to improve my driving.

I encourage you to stick with it, keep going until the temperatures climb again. If you're fuel economy doesn't improve by the summer, let's come back to this.

[JRMichler]

Which is why I track my summer average and winter average mileage separately. The difference is worse on short trips. At -20 deg F, I get 18-19 MPG driving to work, while at +90 F I can get over 40 MPG.

See my sig line.

[MetroMPG]

Bummer story.

Here's my take: you obviously care about fuel economy, you enjoy driving, and you get a kick out of auto technology/engineering.

So sell the Sube and get yourself a hybrid.

I won't be surprised if you recoil at the suggestion, but it makes sense on several levels. (Have you driven one?)

In the future when you can afford both an efficient every day car, and a sporty playtime car, you can get another one.

[ever_green]

thanks guys, but im pretty sure i give up lol 1-2mpg gain isn't helping me and pisses my passengers off sometimes lol. metro i have been thinking about a different car, but not a hybrid. i think that's a bit of a jump for me. I'm thinking of leasing a dodge dart 1.4 as a replacement. Not too sure, just a thought.

[brucepick]

Here are the EPA mpg estimates for the 2013 Dart:
Gas Mileage of 2013 Dodge Dart

Note: The gas-sippier 1.4 litre runs on premium!

In my book, Chrysler has a reputation for fuel-sucking vehicles. I think the Dart is actually Fiat based. Not sure whether that would be a plus or a minus for the car. Of course I'm partial to Hondas these days.

I looked into Subarus as I planned my move away from Volvos in 2008. Subies are very nice (excellent in weather, solid in accidents) but between their shape, weight and the 4WD i think they tend to be thirsty for their size. My two cents.

[ever_green]

as i said its just a thought, im not seriously considering a new car for now.

anyway, i feel a bit better after today. i think i have finally found the sweetspot for my vehicle. Going to work today via the expressway i averaged 8.1l/100km or 29mpg. i was driving at 65mph and during acceleration runs i was using only %60-70 engine load at minimum possible rpm (2700). but then i remembered that's how much my v6 acura gets on the highway :\

So on the way back home with a lot more traffic i decided to drive more aggressively following the official Subaru bsfc chart which indicated a sweetspot of %85+ load at 1500-4000rpm. The problem with my impreza is its churning 2700rpm at 68mph. That's a good thing because i don't have to ever downshift, but it's also bad because of the excess friction during highway cruising. So there is no way that i can accelerate below 2500rpm at +60mph speeds. With 3000rpm RPM and %85-95 load in mind for acceleration runs, i drove home with no special hypermiling technique. I did this as fast as the traffic would allow (+68mph with some slowdowns to full stops). Upon arrival i checked my commute average and it was 7.1lhk or 33mpg. That's a good bit of improvement considering how much easier the drive home was not considering the traffic. There was a WOT run in there too. Funny enough this kind of acceleration technique doesn't work at all in the city, i'm still trying to figure out the sweetspot around town. maybe ill keep this car...

now my only concern is wether the scangauge and my car's on board trip computer were reporting correct numbers. Sometimes they are both off at the pump.

[justme1969]

HMM Well I see the future of the pocket rockett economy cars in the new prius and insight vehicles myself. people are already modifying thier programs to utilize the electric boost during accel. very much like formula one cars now do.
If I could I would have one and modify it just to see peoples faces when thier beaten at a stoplight by a car averaging 65mpg.

I do feel your pain and see your point I went into my kia venture and ups and downs have seriously bothered my driving performance. I vowed that my changes would be to effect car without effecting myself but it doesnt always work that way.
The Kia despite my best efforts want best mpg at 68mph and this means evenhere where all roads are mostly flat 61 at top of hill climbs without adding any load to engine. Well it doesnt take but 1 rig blaring its horn behind me to realize ive strayed from my intent and pissed off another driver.
but I am very pleased with 31-33 mpg now in hindsite because it is above mfg best case lies about the cars showroom mpg. I now have driven it my norm mostly and dont get the old norm of 24mpg when im rolling 77mph on hiway every day.

[ever_green]

yes i think it was my first time getting over 30mpg and i was fairly pleased. 68mph is the right speed for me too (not 60mph). strange considering that my car is running at such high RPMs on the highway. 3k rpm at 75mph and 2.5k at 60mph. uphills dont affect my engine load too much at 68mph but going slower at 55mph may require a downshift to prevent 100% engine load.

[justme1969]

I diddnt realize those cars weighed in at 3k thought they were like 500 pounds less