I've only monitored two fuel tanks and have achieve 24 on the first one and 21 on the second one.

 

I've previously reported my Mazda5 mileage. 2012 version, stick. Now approaching 5,000 miles (purchased April 2011).
Just took a trip from Boston to northern New Hampshire. Drove 60-65 most of the way. significant hills.
miles 345
gals. 10.5
mpg: 32.9

I'm very happy with that. Previously took longer trip to WasDC and got 33 on the highway. So that's my best highway mpg so far, tho I'm shooting for 35, which I think is doable if I get it to 60 mph max.

Has anyone gotten 35mpg with this car?
Has anyone noticed significantly higher mileage when you fill up sooner rather than later? For example, I filled up once in Connecticut on way to DC, just a few gals., and mileage was unbelievable 40mpg. Later for entire trip, mpg averaged 33.

Last week in city driving, filled up before going to NH, and took a few gals, avg 30mpg, when normally I get 28mpg max.
Any idea why that would happen? I am def topping it off each time, so I'm curious about these results. thanks.

 

Unless your fuel economy is averaged over several tanks, the number is highly suspect. Why? Because pumps click off at different points, and so the amount in the tank following a fill-up can vary by over a gallon from fill-up to fill-up. Measuring fuel economy on a short tank will simply cause an even larger variance in your numbers.

In the case of your 40 mpg "short-tank" it is highly likely that the first pump clicked off later and put more gas in the tank than where the second pump clicked off. Had the two fill-ups been reversed you might have been dismayed to find you'd only managed 26 miles per gallon.

 

He could of got some "bad" gas too.

 

I love this topic and it has been a point of frustration along with the insanely high 5 gear hwy rpms.

The facts:
09 Mazda 5 Sport 5 spd stock (other than in dash and roof mounted DVD )
Tires are worn and will soon need replacement (i mention because I believe they currently offer less rolling resistance)

The trip:
1st week of September Atlanta to Seattle w/ wife and two toddlers and luggage pulling an aluminum trailer (more luggage) at 75 mph as much as possible.
Result: 23 mpgs average

The trip (reverse):
this past week we drove back to ATL. no trailer not as loaded, but still luggage and food in the back at mostly 75mph
Result: 31 mpg

We have never seen this mpg. I track my mpg to the nats *** and the last 10k it has improved dramatically. I use the same oil and most of the time I fill up with 10% ethanol, which makes a difference as it has less energy than 100% gasoline. I am not sure if the improvement is from break-in or tires or what. I know that I am less disappointed with the 5.
It will soon get lower with exhaust, maybe we can squeak out a few more mpgs and hps.

 

Lowering your car might eek out a quarter of an MPG under ideal conditions, however, the exaust is unlikely to do anything but reduce your mid range torque (by a very small amount) in exchange for a similar bump in top end (i.e. WOT at Red-Line) power.

 

On mine, I've been averaging 26.8MPG, and my last two fill ups have been Premium Unleaded. I think I can gain another 1 or 2MPG if I use brand such as Shell Unleaded. I try to use Shell exclusively as I don't trust those independent gas stations that sells cheap gas when paid cash. I also have ScanGaugeE installed and will be comparing the two fuel economy data: one from car and the other from ScanGaugeE. ScanGauge does mention that even with accurate data, can be off as much as 15%.

Also, when I owned a Mk4 Jetta, I used to know someone who had a VAG-COM whom used to set my transmission shifting preference on Economy which used to help me get better fuel economy. I am wondering if Mazda has that as well? Maybe by default, from the factory, the transmission shift points are set to Performance or Adaptive. I wish I knew if I can change it to Economy mode - i.e. shifting points are sooner.

Next is using tires with low rolling resistance. I particularly prefer brand/make such as Michelin MXV4 Plus as not only I've gotten 100K+ miles out of the set on my last car, but also, I notices 1 to 2MPG improvement over softer tires which gave me better dry weather traction.

Finally, here's a good write up on maximizing fuel economy. Some are sillier than others and a lot of them are common sense. But, I did pickup on a few suggestions like removing things like mud guards which impedes airflow (though in minute amount) if left on. Or underbelly covers which helps with aerodynamics.

http://ecomodder.com/forum/fuel-econ...ifications.php

 

You might very well see that 1 to 2 mpg gain by simply using Regular Unleaded instead of Premium. Your engine was not designed to run Premium fuel, and if you do your engine will suffer an accelerated build-up of combustion chamber deposits, and will, eventually, require Premium fuel because of those deposits (and the hot spots they create).

 

This is good because I can "kill two birds with one stone" if you will. Though I don't like that adage just thought I use it here because haven't used it in a while

Okay, so my next tank will be Shell Unleaded. I don't like ethanol mixture however because I think my fuel economy will suffer. I will post another message once I start using unleaded. I am still breaking in the engine if you will and I think the mileage isn't that great during that period. I am anticipating doing a lot of fuel saver mods down the road to hopefully get around 31-33MPG on highway.

 

18.5? Somethings not right. I consistently get over 26.7MPG combined driving.