Last post on Dec 07, 2011 at 2:17 PM
You are in the Mazda Mazda5
What is this discussion about?
Mazda MAZDA5, Fuel Efficiency (MPG), Van
#398 of 437 Re: Low mileage with the 5 [davempls]
Jan 05, 2011 (12:36 pm)
the trick isn't just the low rpms, but also the foot to the floor and upshifting. It means you are in the lower gears for as short of a time as possible while not revving too far, either. In other words, getting to 5th gear as fast as possible and staying there as long as possible.
#399 of 437 Re: Low mileage with the 5 [qbrozen]
Jan 05, 2011 (1:11 pm)
That is a very valid point. re the formulation of the gas. keep in mind that you get about 10% less gas mileage when there is ethanol mixed with it at about a 5% ratio. and they tend to add extra to winter gas (because it absorbs water). Remember gallon for gallon, pure ethanol contains one-third less energy than gasoline. The other side affect is that ethanol is very corrosive which is why they can not use pipelines because of it. The Mazda 5 is not designed to be used with ethanol so I would avoid it anyway. The ethanol industry say you can us up to 10%, on any car, but to me that is like saying you can eat a small amount of mercury and not die lol
#400 of 437 Re: Low mileage with the 5 [qbrozen]
Jan 06, 2011 (11:53 am)
The thoughts about shifting are interesting.
I checked the manual and it says the proscribed speed to upshift from 2>3 for "cruising" from would be at 18 mph, and from 3>4 29 mph.
I've pretty much always shifted my manuals over the years from 2>3 at about 27 or 28 mph, and from 3>4 at 38 or above (with adjustments for hilly conditions, etc.).
Assuming their recommendations take into consideration fuel economy and general engine health, it looks like I might benefit from lowering my shifting points quite a bit.
It also has a grid with general upshift recommendations for "acceleration", which I presume would be not for cruising but accelerating to top speed - which specify 24 mph for 2>3, and 34 mph for 3>4.
Either way, I come out well above those numbers with my usual practices.
I've always felt funny cruising along for any length of time with the tachometer stuck down on the lower end of the register, feeling like it might be putting undue strain on something in the engine or transmission. (Worst case scenario, sitting in the passenger seat while someone else rolls around a corner in third gear...!)
Is there an optimal range to observe for rpm's?
#401 of 437 Re: Low mileage with the 5 [davempls]
Jan 06, 2011 (12:14 pm)
An associate in the emissions testing field once told me that low rpm / larger throttle openings / early shifting will produce better fuel economy, so I've been following that for a while (and of course, no more "larger throttle opening" than required). These modern, electronically-controlled engines are amazingly tractable (IMHO, having owned 4-cyl cars since the 70's) so much of the old-days "lugging/knocking/danger" advice rarely is needed. As well, w/r/t your concern for strain on the drivetrain, at low rpms the engine is well off its torque or hp peak ratings, so no worries there either.
My Sport5MT is usually in 5th at 40mph, no issues, and I tend to use the tallest gear that works in the given situation. Which is, actually, how many modern automatics are programmed for best fuel economy (to the point where enthusiastic drivers will gripe, for vehicles where "kickdown" to a lower gear doesn't occur quickly/seamlessly).
Just a data point.
#402 of 437 Re: Low mileage with the 5 [davempls]
Jan 06, 2011 (1:24 pm)
I concur with ljmattox's post.
As to your question... if I'm dealing with low-speed city driving, I only look to keep it at 1500 rpms or above. So if I'm driving so slow that 4th gear puts me at, let's say, 1800, but 5th would be 1300, then I use 4th. If you do need to put your foot down while cruising at such low rpms, then you simply downshift.
Let us know how you make out.
#403 of 437 Re: Low mileage with the 5 [qbrozen]
Jan 06, 2011 (6:14 pm)
Good to know - thanks for all the info. I have a full tank as of today, so I'll report back when I next check the mileage.
#404 of 437 Re: Low mileage with the 5 [davempls]
Jan 19, 2011 (7:02 pm)
Since you get very good hwy mpg, I'm guessing theres nothing wrong with your car, and your poor city milage is due to your driving style.
I get around 27mpg in city driving without trying too hard, but there are a couple of tips for manual shift 5's.
1) Avoid going over 3k rpm. At 3k, the variable valve timing shifts into the power mode, making much more power but also eating gas.
2) Use engine braking to slow for stops. When the motors over around 2k rpm and you're off the throttle, the fuel injectors shut off completely.
3) Short shift at around 2k rpm using fairly light throttle. The car makes good torque and can pretty easily keep up with traffic.
4) always use the highest gear you can without the motor straining, incuding speeding back up after slowing down. The 5 will accerate from 35 mph in top gear just fine, and this helps economy considerably.
I do all 4 of these techniques without even thinking about them now, and passengers normally don't even notice I'm doing anything out of the ordinary.
#405 of 437 Re: Low mileage with the 5 [dean1966]
Jan 20, 2011 (12:19 pm)
Thanks. I've been trying to do all those things this last week (since I last filled up), so we'll see!
So far it doesn't *look* good, judging from the needle on the fuel tank gauge, but I'll have a better idea in a few days. I think I could work on the engine braking a bit, as that takes a bit of practice in the city...
#406 of 437 Re: Low mileage with the 5 [dean1966]
Jan 25, 2011 (1:35 pm)
Well, I spent the last week employing all of the above techniques to save on gas in city driving - keeping the rpm's low by upshifting at strategic points, engine braking, etc.
The verdict is in, and my city mpg for this last tank was a whopping 16.6 mpg, and using premium gasoline at that!
It's a far cry from your 27 mpg in the city!
Oh well, I'll keep at it. Maybe it'll improve with practice, or there's something else I'm missing... (?!)
#407 of 437 Re: Low mileage with the 5 [davempls]
Jan 25, 2011 (3:38 pm)
You are making sure you do not use gas with any ethanol in it, when trying to get the most mileage from a tank. I hate the say the obvious. The Mazda engine is not designed to use ethanol but can tolerate up to 15%. If you are using gas with it in there you can lose up to 1/3 gas mileage depending on the strength. All of Mazda's and government figures use non ethanol gas for testing.