Hey guys, new here

I have a 1 year old Mazda 3 1.6 auto and it wastes a lot of fuel

I filled it up today with 46 litres which only got me 370km from the tank.

The car has 13,500km, is serviced as per the manual, 32psi tyre pressure, no air con usage, sometimes the window is open a crack for air. The car is warmed up for a few minutes before each trip as well, and I drive it very sedately. The driving is mostly city driving, but even if I put 200km of highway driving it'll still only get maybe 40-50km more a tank.

I am wondering if there might be something wrong with it? Like Ecu or the O2 sensor or something?
I have a 1994 2.2 auto E class which uses about the same amount of fuel, but is a 2.2, is old, and heavier, and is subjected to much harsher driving.

Any ideas? Or is this normal to be wasting so much gas?

 

Was it getting better mileage when you bought it?
My 2.3 is getting around 580KM per tank.

 

Also it depends on the Fuel you are using, it will get a lot worse mileage if the fuel has a high ethanol content.

 

No it always had the same poor consumption from day 1
The fuel I use is 98 octane. I am not sure of ethanol content, but the fuel smells funny here compared to other countries I've been to. Is this a sign of high ethanol content?

Tell me, on your trip info, what is your average speed and average fuel consumption?
On mine it shows 30km/h average speed and 11.0/100km average fuel consumption

 

Two things stand out to me:

1) Warming up your engine as you do is both a waste of fuel and harmful to the engine.

2) Check your Owner's Manual to confirm this, but I believe the fuel your using (which I assume to be 98 RON) is WAAAY too high of an octane for your engine. Assuming I'm correct here, using this fuel can cause significantly reduced fuel economy.

 

I don't have the Trip Info, but going by your average speed it seems to me you do a lot of stop and go or just slow driving (Around Town).
On my 07 my average speed was between 40 and 50 MPH (64-80 KPH) and was still getting 550km per tank.

And with what shipo said, what does your Manual say for Octane you are supposed to run.
Also, where are you at, here in the US 93 octane is as high as you go without buying racing fuel.

 

Ditto that -- 87 octane is sufficient. Warmups only benefit the occupant -- not good for mileage or the motor.

 

93 octane? That's pretty low. What happens if you own a performance car? And what happens to Honda Type R's which need higher octane fuel?

I am living in Cyprus. I haven't seen 93 octane fuel here. 95 is there and it goes to 102 RON.

Normally the higher the octane the more mileage you get. The last tank I filled up with 95 so I'll see how it goes

As for warming it up, it's not bad for it to warm up. Keep in mind I mean a few minutes for the oil to circulate everywhere and the temp gauge to get onto the dial. After that I drive it very slowly until temps builds up (only takes 2 minutes or so) and still I take it easy for 10 more minutes to wait until oil temp builds up as well.

The driving is mostly stop and go + traffic driving. A lot of the times the car never has a chance to get out of 3rd gear. Either way the fuel usage seems too high for a 1.6 motor

 

Yes, I suspect that your car calls for 93 RON (which roughly equates to 87 AKI here in the States). As for what happens to "Performance" cars that need higher octane fuels (i.e. fuels that have a greater resistance to detonation), as the compression ratio goes up (or as the boost in increased on blown engines), the need for higher octane fuel goes up.

Yes, I've noticed in other parts of Europe that 93 RON is pretty hard to come by and that the lowest grade of fuel is typically 95 RON (which equates roughly to our 89 AKI "Mid-Grade" fuel).

As with most things in life, "It depends." If you have a lower compression ratio engine (typically 9.5:1 or lower), then 87 AKI / 93 RON is typically the fuel that will deliver both the best and the best fuel economy (and even here "it depends" as the new Honda R18 engine has a 10.5:1 compression ratio and yet it still calls for and delivers the best economy on low octane fuel).

Case in point, my Mazda3 i (with the 2.0 liter engine) has a 10.0:1 compression ration with a fuel requirement of 87 AKI.

Keep in mind that if you are using the correct oil (and in Cyprus even if you're not), then the oil should be circulating "everywhere" within three to five seconds, and if it isn't, then you have some much bigger issues to deal with than poor fuel economy.

FWIW, even when it's -25°C around here engines running with 5W-30 oil (the oil I suspect your Owner's Manual calls for) achieve full oil flow within a couple of seconds.

Long story short, it seems fairly obvious that a combination of your driving environment, the fuel you are using, and the inordinately long warm up period are all contributing to your poor fuel economy.

 

I don't think my warm up periods are extremely long.
Ok, once in a while when I start the car and then need to go do something it'll be about 5-7 mins but usually 2 mins is all I wait.
I heard it takes about 1 minute to completely lubricate the whole engine from start up but I don't have expert knowledge to back it up.


Maybe though the USDM Mazda 3 is different to the EU spec Mazda 3? American cars usually have larger seats (average American is overweight) and have softer suspension (comfort over handling I guess) and also have different emission levels.
So, I suspect that maybe the CR is different and the EU Mazdas are designed for higher octane fuel


I have however filled up on 95 the last tank and I will see how it goes