View Full Version : My Situation
05-31-2007, 01:10 AM
My car is a Mazda 6i 5speed. I commute about 46 miles each day round trip, 40 of which are highway. My big advantage is that I work swing shift, so I avoid rush hour and can pretty much keep an even speed the whole way. Sometimes I can even get a "pull through" parking space at work. At home my driveway is inclined just enough so that when I get in my car, I can disingage the parking brake and coast down to the street and get facing the way I need to go before I have to start the engine, so that helps too.
I've been getting between 30 and 32 mpg so far without trying too hard. I just increased the air pressure in my tires, and I'm going to try and keep it at or below 60mph. The goal is to get to 35 mpg and possibly beyond.
A few questions:
Is it best to keep the RPMs as low as possible at all times, just above where it would start bogging down, or is there a more efficient engine speed a little higher up the scale? 2000? 2500? Depends on the car?
And secondly, do fuel cost savings from using synthetic motor oil completely offset the added expense? Thanks,
05-31-2007, 01:28 AM
Welcome aboard, pumaman. I'll do my best to help here.
Your question with RPMs has no easy answer as much depends on the grade. On the rare occasion I travel the valley floor, which is decently flat, the lowest possible RPM I can keep without bogging the engine always nets the best MPG. In this scenario it is rare for me to breach 2,000 RPM.
However, on my usual commute over the mountain I have found that once the grade is 4% or better each gear has a "sweet spot" that yields the exact same MPG that the sweet spot in the previous gear did. In other words I get the same crappy uphill MPG at 2,600 RPM in 4th gear at 50 MPH as I do in 2nd gear at 2,600 RPM and 30 MPH.
I take it the area you drive in is low, rolling hills? If so, try to accelerate and brake very lightly and keep the RPMs below 2,000.
Times like this are where a ScanGauge II comes in handy as it gives a real-time MPG/GPH report that let's you dial in in the "sweet spot".
05-31-2007, 07:20 AM
As for the rpm. Lower is better in most case's. How low and where your cars sweet spot is, only you can find out.
As for the oil. I use M1 syn. in my Hondas. My Ranger dislikes M1 for some reason. It rattles and burns the stuff. So I run Motorcraft oil in it. And its very happy with it. A 0w-20 or 5w-20 will have better friction reducing numbers. Its thinner oil. But the big thing is. You can run the syn. oil a lot longer. If your a 3k mile oil changer. You can easily go 6k miles per change on a good syn. I change oil in the Hondas between 8k and 11k miles. I let the Accord go to 15k miles once and it was two far. The valve train started to get real audible. I also do a fluid change on the transmissions every third oil change.
When driving for FE three things will happen. You will become a far better driver. You will become more in tune with your car. And you will maintain your car better.
05-31-2007, 08:03 AM
With such a straight cruise, it sounds like you aren't stopping much. That's excellent - no idling time. Most of the miles you spend at a steady speed, which means highest gearing (at 50-60 MPH). In the M6i 5MT (I4 or V6?), 5th gear is perfect for highway cruising. Pump up those tires to max sidewall (usually 44 PSI) and let'er run. If the car is new(er), it may take some mileage to even out your MPG, but you should see the upper 30's in no time.
Great job on the Face-Out parking situation! :)
05-31-2007, 08:21 AM
You should take a look at the Pulse & Glide section here. I think you will find that you get a huge improvement in mileage from that, I know I did. It seems counterintuitive that varying speed would give better mpg than constant speed but it does: gliding adds "free" miles into the equation.
Also, get a Scangauge so you can see what you are doing.
05-31-2007, 10:19 AM
Thanks for the info so far, I'll have to research the scan gauge thing and see if I want to try that.
I live just West of St. Louis, where it is flat with some rolling terrain, and only the occasional steep hill coming up a bluff from the river bottoms. The RPM question was assuming being on the flat, but that's good that I can look for a different sweet spot when I have to go uphill.
The engine is the 2.3l I4. Once my vehicles are broken in I go to a 5k oil change schedule since my wife and I drive mostly highway and it's easier to remember. (BTW don't ask about my wife's driving habits :^) I'm using 5w-20 in the Mazda 6 which is the first car I've owned that can use that thin of an oil according to the manual.
Don't know about the pulse part, but I've begun taking the car out of gear on the downhills and letting the engine idle (unless I get going too fast).
Here's another off the wall question I just thought of. I eat fast food two or three times a week. Do ya all park and go inside, even when you're getting food to go, rather than sitting in the drive through?? For awhile now, I've taken to turning the engine off while I wait in line. Heck, at the Taco Bell, the lane from the speaker to the window is downhill so I can keep the engine off the whole time! And of course the SUVs around me are idling away... but sometimes I wonder if I might just be better off parking.
05-31-2007, 10:31 AM
I eat fast food two or three times a week. Do ya all park and go inside, even when you're getting food to go, rather than sitting in the drive through??
Welcome, Pumaman! I almost always go inside, but for reasons unrelated to hypermiling. Simply, when I'm hungry I'm impatient. Multiple lines inside are usually shorter and move faster than one drive-through line.
For your other questions, others here are much more qualified to answer. My hypermiling experience is limited to the Prius, which uses substantially different techniques than conventional cars.
05-31-2007, 10:35 AM
On the rare occasion that I go to a fast food eatery, I almost always go inside. With the flat terrain of FL coupled with a longer wait time, you can usually get your food faster inside. Although I will admit, sometimes it seems like they favor the drive-thru more. :?
xcel has lots of good things to say about the 2.3L I4 you have in your M6 - he has it in his Ford Ranger and is pushing 50 MPG, IIRC. Feel free to shut down for 10-15 seconds as long as you're operating at NOT. It won't harm the starter - engines will come back to life easily when properly warmed up. I shut down and nearly every light now, even if I know the wait is 15-20 seconds, as long as I'm warmed up.
5W-20 is good oil - for now, I'd stick with it. No need to go thinner, especially on a newer car.
And pump up those tires! :D Good luck!
05-31-2007, 10:59 AM
I would agree with psyshack that synthetic oil per se will not improve mpg. It helps when you can use a lower viscosity oil. Not all engines do well with thinner engine oil so this would be a case-by-case decision.
Used oil analyses indicate that the Prius engine (for example) seems happy with 0W20. But not much of that sort of data is available yet, particularly for hybrids.
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