2015 Mazda 6, easy 40mpg

[Dean in Milwaukee]

We bought a new 2015 mazda 6 sport with the manual shift a few months ago and just got done with our second road trip.

The car is as delivered with the tires at the max of 50 psi instead of the recommended 45psi, and all I did otherwise is use the cruise control set right at the 70 mph limit, and the car again got just over 40 mpg for the trip.

Most of the time the econ gauge is hovering in the low 40's, slight uphills drop it into the low thirties, bigger hills into lower 20's, but on the backside of the hills mileage will often jump into the sixties or even 70's. It makes you really notice hills.

Around town my wife is averaging about 30mpg most of the time which is pretty good for her 5 mile all city commute.

According to mazda the car has a low Cd of 0.26, and the gearing is pretty tall in 6th, about 2200 rpm at 60 mph. The result is an effortless 40 mpg hwy, and I suspect you could do much better yet by hypermiling it.

Dean

[BabyDiesel]

Great numbers from a newer vehicle, especially at 70 mph. That Cd is remarkably low, on par with the Prius and Insight. 50 mpg would not be too difficult with your vehicle IMO.

[Dean in Milwaukee]

This being my first vehicle with a fuel econ readout, I have noticed some counter-intuitive things.

If I don't use the cruise control, and instead just hold the throttle very steady, fuel economy doesn't climb and fall up and down hills barely at all. even though the cars speed is varying. I can maintain 50 plus mpg for long distances if there are no cars backing up behind me doing this.

The other is that very gentle acceleration from stops is not the best plan. Taking off slow keeps econ readout steady in the low teens until I finally reach speed and get it into 6th where the high numbers appear.
I get better average fuel econ by taking off at fairly heavy throttle and let it rev to get up to speed quickly, getting only 8mpg, and then skip most gears right into 6th as soon as I'm going fast enough to do so.

As far as the low Cd and the low rolling resistance tires coupled with the very tall top gear, leaving hwy travel requires me to get off the gas way earlier than my previous cars as the 6 just wants to coast forever without slowing much. I actually need to downshift to increase engine braking while still on the hwy if I want to avoid significant brake use at the stop sign at the end of the off ramps.

The other thing I'm liking is the cars hwy range. 40 mpg and a 16.4 gallon tank means a safe range of 600 plus miles. Its almost as good as owning a diesel.

Dean

[kafer65]

We've got to bring you into the Mazda fold. Get signed up for team Mazda! We need to give the Honda guys a little competition (secretly also a fan though). Sounds like yours is behaving just like mine. Are you running the 2.5 liter four or the V6?
Wheel covers I was surprised at how comfortable the ride was even at 20% over max sidewall. Partial grill block, scangauge and careful use of AC and I bet you could be doing 50mpg at 55 mph and still be fairly ecostealth if thats your thing.

[user removed]

Throw it in neutral and coast down those hills and watch the fuel mileage go over 200.
Downshift to slow down, or even let off the gas in 6th and your instantaneous mileage goes to infinite. Anticipate having to slow down down shifting instead of braking.

regards
mech

[Dean in Milwaukee]

The 2015's only come with the 2.5 4 cylinder, no 6 is available. It does get up and go if you want though, 184 hp and 3100 lbs is quite decent.

The econ gauge maxes at 99 mpg, but it does that every time the throttle is shut at any speed over 10 mph.

As is, setting the cruise at 60 or so causes the econ gauge to sit in the 46-48 range, again so long as there are no hills or significant headwinds.

The only mod I may do would be a partial grill block, but I would have to make it invisible so the Missus won't mind.

[Dean in Milwaukee]

Took another short hwy trip, caught a traffic jam but this was balanced by most of the trip being 65 mph instead of the 70 mph of the other two trips. I'm pretty pleased with doing 41.3 mpg again by just setting the cruise control and driving.

I wonder if the car could still be breaking in at the 3k mile mark?

[solarguy]

Yes, it is still breaking in, and you should see a modest improvement by 9-10k miles.

[kafer65]

You may be able to see a slight improvement compared to my first fuel logs(I'm at 20k miles now). There are all of the mods since then to consider as well.

[civicefficient]

Nice numbers what low rolling tires does it come with? I'm looking at upgrading my car from cheap tires to Goodyear Assurance Fuel Max tires.