2011 Mazda 3 fuel economy

[Captain Mazda]

Have you done a fuel line flush yet?

[Woodnut]

When I first bought my Mazda I was disappointed with the fuel usage. It was no better then the Mazda3 I just traded in. But I have been doing some playing around. Here are a few things I found.
When the gas light comes on I still have 120Km left in the tank. There is about 45 - 50Km before the last light goes out and about 70KM before you run out, and yes I have miss calculated a few times and have run out. (3 times)
I know a lot of people don't like using the bottom of the tank, but I have always done it with no problems. By doing this I went from 450 - 500 to 500 - 600+km per tank. This is a combination of mostly city driving and some hwy.

For the last 6 months I have been working in London Ont. I live in Burlington, so round trip is 260 - 300 per day. So I really started to play around with what I can do so I am not filling up every 2 days or less.
Today I rolled the trip odometer. When I pulled into the gas station I was 1011.5 KM for a single tank. How? I over fill the tank. I slowly started putting more in every fill up. Last fill up I was able to put in another 15L of gas. My gas light had just come on and the price was down at the gas station. The pump popped at 41L. I overfilled it to 56L. The first light on the gas gauge didn't go off till I hit 320KM. By half tank I was at 600KM. when I finally drove into the gas station (3rd day on this tank) I was at 1011.5 KM and the pump popped at 48L. From My calculations I still had about 7L left, but I didn't have a gas can and wasn't going to push it any more. Now I do 98% hwy driving. I keep my speed down to 110km - 120km. No A/C and only use front defrost when needed. I do carry about 200lbs of tools in my car. For gas I just use the cheapest, usually from Husky. I have 209000+ km on my car. Still have the originally spark plugs. I don't always change the oil on time but did change the trany oil at 200K
Don't take my word for it, go out and see how far you can go (bring a gas can if you are really going to push it). I am sure every car is a bit different.

NOTE: Yes I know you not suppose to over fill the tank as gas needs to expand. I only do this before I drive 1.5hrs to work or on the way home. So far I have never seen or smelled gas around my car. I don't recommend over filling it this much and just letting it sit.

[Booter22]

@Woodnut as much as i like your story i wouldnt advise to overfill it that much at all. maybe 2-5L max maybe. but 10-15 + L is way to much to overfill regardless of how far you are driving right away.

[G ~ MINI]

Currently at about 7liters per 100kms...mods and tuned for extra HP and im always in gear and always spirited driving mode.

For those older high mileage engines ...time to clean out all those years of gunk
Im biased toward Liqui Moly ..love their stuff. Recommending you do.
(Liqui Moly preferred or another product)

Fuel system cleaner then do a Engine oil Flush and fill with MolyGen 5W30 with a high flow oil filter
https://www.liqui-moly.us/en/products/molygen.html

I know the non turbo require 0 weight oil but as your engine gets older wear n tear increases so does the gap between metal parts
and a little bit thicker oil helps. Besides...this product is formulated low friction and also has alot of
anti fiction stuff included that it runs like a 0w30..(no additional anti fiction needed) .
And its Green ... tbh i got it because it was green...lolol... it florescent green so any leaks are detectable ....

[Booter22]

Over the 173 000 km i have tracked im about 7.3L/100 km with a cold air intake, mazdaspeed cat back exhaust ( no tune) . running 0W20 for most of the engines life the odd time 5W20. she sees redline a few times a week, my last tank managed to get 5.1L/100KM my best over was 4.3 somehow. overall.. have spent $16,000 in fuel.

on a sad side note about the actual cost of fuel.. my jeep grand cherokee 3.6L V6 has tracked 77,000km and averages about 10.9L/100km i have spent about $9,555 so far.