Mazda2 gas mileage and defrost problem

[punkrck4sissies]

Hi there. First time Mazda owner and first post.

I just bought a 2012 Mazda2 Sport yesterday afternoon. It was a cold and rainy day and we took it to visit family about 70 miles away, mostly highway (the speed limit varying between 55 and 70mph).

The first thing I noticed was that we used more than a quarter tank just on the way there. We also own a 2008 Toyota Yaris 2 door hatchback, so I'm comparing it to that. It wasn't until the drive home when it was dark out that I noticed the air conditioning button was pushed in along with the heat and defrost on. I pressed the ac button to turn it off, and the defroster stopped working. I tested it a few more times and it was the same each time- no ac, no defrost.

I know this isn't normal, but could it also affect my gas mileage? On our trip we averaged 22 mpg.

I'm calling the dealer tomorrow, but I'd appreciate any input.

Thanks!

 

[firespirit]

I don't see why you are getting anything less than 29-30mpg. Might be something wrong because I've been getting 32mpg on my 2011 Sport automatic (and that's not babying it)

 

[punkrck4sissies]

I forgot to mention that it's an automatic.

 

[DrWebster]

The defrost should work without the A/C on. In fact, one of the nice things I've noticed about the 2 is that when you turn the vent knob to defrost, it doesn't automatically turn on the A/C for you (which a lot of cars do). But yes, having the A/C on will definitely have a negative impact on your fuel economy.

You should still be able to get good gas mileage even with an automatic; my car is an auto and I regularly get 38-40mpg. 55mph seems to be the sweet spot, but even at 65-70mph you should still see about 35-36mpg. 22mpg is way too low; I don't think I could get my car to do that even if I tried. Maybe the parking brake was stuck on slightly, or you pressed the Overdrive Off button on the shifter (the little button below the main one) to disable 4th gear? Do you remember what your engine RPMs were like during the trip? Should have been in the 2500-3000 rpm range.

 

[punkrck4sissies]

I really don't think the parking brake was on, even just a little bit.

The defrost thing was crazy. It literally didn't work at all unless the a/c button was pressed in, then once pressed, worked right away.

I actually did keep an eye on the RPMs and they were in a good range. We just traded in a 2006 Honda Civic Hybrid that revved up way too much and got terrible gas mileage, so I made sure to pay attention. Everything in that department seemed normal.

We used half a tank of gas on around 140 miles.

 

[jonlep]

you're on recirculation for the air. You cannot use the defrost on recirculation of air, but it works only when the AC is on.
your car is brand new with the AC on, it doesn't help the fuel economy.
Just ride it and do a couple of fuel check up, you'll see it getting better each time

 

[MyPrecious]

Don't judge your fuel mileage based on the rate the fuel tank goes down. I have noticed that the fuel gauge is calibrated such that you have burned considerably less than half the fuel load when the gauge is down to half.and it drops much more slowly on the second half of the tank. This rapid drop on the first half of the gauge takes some getting used toit kind of messes with your head until you get a feel for how it behaves. Fuel gauge behavior asideI have an automaticand I typically get the rated 27 mpg in townand the rated 33 mpg on the highway if I am running 65 to 70 mph with the AC on.

Nowas to defrostingread your owners manualit gives a very clear understanding on how to use the air handling system for best results in various conditionsbut in cold wet weather like you describewhich is also very common here in Indiana.we had it Friday.you had it Saturday.you will want the recirculation control on fresh air (not recirculate).you will want to have the AC on.button pushed in so it lights upand then adjust your temperature control so that the air is warm enough that you are comfortable. Additionallyyou may need to run the defrost button on your rear window to clear it initially.

Once you have run the car for 4 or 5 milesonce you get the windshield clearedyou can turn off the rear defrost and turn the air distribution dial so the air is coming out the top vents (versus defrost where the air is all directed toward the windshield). I find this keeps the windows clearand the passengers comfortable better than running on defrost continually.

YMMV

 

[Racebrewer]

Also as indicated above, the car is brand new. If everything was constant your gas mileage will improve tank by tank until you get to about 60,000. At that point it should level out until about 150,000 before it starts a slow decline until a valve job is done.

That's given proper maintenance and a reasonable level of abuse.

John

 

[Max Archer]

The car still has like 1/4 tank with the gauge at empty. I filled it when the E and the last black "bar" were flashing, and it took a little over 8 gallons, so there were almost 3 left in the car.

I've noticed that I get better mileage with every tank. My average has gradually been going up and up.

According to the owner's manual, the A/C dehumidifies the air and has to be on, even if it's turned to warm, when the defroster is on. I did notice that with it off, the windows fogged up pretty quickly when it was cold and humid.

 

[arcxer]

We used half a tank of gas on around 140 miles.

Look, firstly half a tank judging just by the fuel gauge might not be exactly half a tank. Like already said, filling it up with E flashing usually is about 8 gallons. If half a tank is half of that -- say, about 4.5 gallons -- 140/4.5 ~= 31 mpg (not spectacular, but it's a new car, so...)

And indeed, I wouldn't try to guess mpg by the fuel gauge -- it's not linear (taking it that you have Sport, so no trip computer -- that one lies too, but differently ) Use Fuelly, or just your own calculations, but not those little LCD bricks...

 

[firespirit]

Look, firstly half a tank judging just by the fuel gauge might not be exactly half a tank. Like already said, filling it up with E flashing usually is about 8 gallons. If half a tank is half of that -- say, about 4.5 gallons -- 140/4.5 ~= 31 mpg (not spectacular, but it's a new car, so...)

And indeed, I wouldn't try to guess mpg by the fuel gauge -- it's not linear (taking it that you have Sport, so no trip computer -- that one lies too, but differently ) Use Fuelly, or just your own calculations, but not those little LCD bricks...

I use an app on my Android phone to calculate my fuel mileage Every fill-up all I have to do is punch in how much per gallon I paid, how many gallons I put in, and what the mileage is on the car. I love my app!

 

[punkrck4sissies]

Thanks for all the advice! I'm going to keep an eye on everything. I haven't had time to read the manual cover to cover yet, but I'll definitely check out the section on air handling.

I've never had this problem with any other car, so I assumed it was some sort of error. Once I got into work, two of my coworkers said they have to do the same thing.

I also didn't know that the digital bars aren't reliable. I'll check out some apps today.

Again, thanks for the advice. I'll keep everyone posted on how the second half of the tank goes.

 

[MyPrecious]

Many cars.....like your Yaris...automatically turn the AC on when the airflow dial is set to defrost. Some folks like this...I personally like that this is not automatically the case on the Mazda....I prefer to turn the AC on when I need it to defog...and leave it off for better fuel mileage when I don't.

You will likely get better fuel mileage out of your Yaris than you will the 2...but the 2 is much more fun to drive IMHO...

 

[robmilkshakes]

The AC is supposed to come on with the defroster. It serves two purposes, it removes most of the moisture from the air that could condense on the glass worsening the problem, also it prevents vast temperature differences on either side of the glass (for example when it is very cold out, blowing very hot air on the inside of the glass, or visa versa) that could cause a windshield to crack.

As for the fuel consumption, I've yet to find a fuel gauge that is reliable hahah. As it has been said though, the fuel mileage will improve as the engine breaks in, at ~4000 miles now, my fuel economy under the same conditions has increased by 4mpg.

 

[jonlep]

again, you can use the defrost as long as the bottom level is switch to fresh air, not recirculate and without the A/C.
Do you think we use the A/C to defrost our windows in winter in Canada ?
switch to FRESH AIR, not RECIRCULATE !(whistle)

 

[arcxer]

The AC is supposed to come on with the defroster.

Well, how about cars which don't have AC?

Yes, A/C certainly helps by drying out air, and in certain situations it's needed, but not always.

 

[MazdaTwo]

Thanks for all the advice! I'm going to keep an eye on everything. I haven't had time to read the manual cover to cover yet, but I'll definitely check out the section on air handling.

I've never had this problem with any other car, so I assumed it was some sort of error. Once I got into work, two of my coworkers said they have to do the same thing.

I also didn't know that the digital bars aren't reliable. I'll check out some apps today.

Again, thanks for the advice. I'll keep everyone posted on how the second half of the tank goes.

I have 2 and my wife has a Yaris, much like your situation. Unlike the Yaris (and many, many other cars) the Mazda 2 puts the fuel tank buffer at the bottom end instead of the top. Most cars (including my wife's Yaris) can get up to 75-150 miles on the tank before is shows much fuel consumption on the gauge; however, once the tank on the Yaris says empty... It's damn close to empty. On the 2 (as others have stated) you only get about 40 miles before the bars start disappearing. The upside, is that you can drive it until the only the "E" remains and still only pump 9.5 gallons into the 11.3 gallon tank.

The general consensus seems to be that Mazda did this to ensure that the fuel pump is submerged which will increase the life of the pump.

 

[PGTBrow]

Shoot, 22mpg is like a 90+ mph trip. I avg 65-85mph while I commute and still get 31.1mpg lol. Something is def a little odd because my AC does effect mpg of course, but not that much.

 

[Joker2]

The AC is supposed to come on with the defroster. It serves two purposes, it removes most of the moisture from the air that could condense on the glass worsening the problem, also it prevents vast temperature differences on either side of the glass (for example when it is very cold out, blowing very hot air on the inside of the glass, or visa versa) that could cause a windshield to crack.

As for the fuel consumption, I've yet to find a fuel gauge that is reliable hahah. As it has been said though, the fuel mileage will improve as the engine breaks in, at ~4000 miles now, my fuel economy under the same conditions has increased by 4mpg.

This is true for most cars but not all. While today it is common to have AC on most new cars, some are still available without. Defrost is a function of circulating air of equal humidity and temperature levels on both sides of the windshield. That is uncomfortable, and the first step is to heat up the fresh air (aka my old Beetle 1973). AC dries the air and speeds up the initial defrosting process, but it must be ON to be effective. If you can defrost with fresh air, and do not cycle the AC, your fuel economy will improve. It was common in older cars to disable the AC from automatically coming ON when the defrost button or knob was selected. I like the Mazda 2 set-up much better than that of other cars I have owned. That being said, the sweet spot for our tall & short bodied (aerodynamically speaking) cars, is about 40-55 mph where they average over 40 mpg with ease.

 

[ngd298]

You have to squeeze a gallon or two extra into the gas tank after the pump kicks off or else the gauge doesn't stay on full very long at all. So far it hasn't harmed the car at all and it adds 50-70 extra miles to the tank.