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Mazda 3 sport automatic. What is your fuel consumption IN TOWN?

  • 15-20 MPG

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  • 20-25 MPG

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Discussion Starter · #1 ·
Hi - I just bought a Mazda 3 2018 sport automatic and I love it, but... Fuel consumption for me driving only in central London is around 19.5 MPG (or 12l/100km, or 8km/l).
Is this normal?
I had read reviews with figures almost twice as good...
 

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2020 Mazda3 Saloon in Soul Red Crystal.
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Your MPG does seem low. I wouldn’t be expecting 40 MPG but I’d hope for around 30.
But…..you’re driving in central London so will be mainly start/stop driving at an average of only around 12 - 15 MPH. It’s winter so you’ll be using fuel to run a lot of electrical items, heater, lights, wipers etc.
Accurately check your MPG by filling the tank to the brim, driving for 25 - 30 miles, refilling to the brim & dividing the miles driven by the fuel used. (Example: miles driven = 30, fuel used = 7.6 litres = 3.9473 miles per litre x 4.5461 to give an MPG of 17.9447).
If the above confirms your MPG at around 20 then take the car somewhere less urban & see what MPG you get.
 

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Discussion Starter · #5 ·
Thanks - good tip to measure it again without waiting for data on the full tank refill - but at the moment my consumption looks scarily bad - having gone though 3/4 of the full tank in less than 2 weeks, with only 2 x 40 miles trips on theM4 and no more than 2 x 3 miles trips a day -for an estimated 6m X 11 days = 66m of urban drive + 80 miles on motorway, for a total of 144 miles with 34 litres!!! Which is again less than 20 MPG. I have just filled the car again and recorded the current mileage, so within a week or so I will have some more accurate data to evaluate. If I still find out that the consumption is that bad, what are my options, considering I just bought this from a second hand dealer?
 

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I don't know if it's too low but your mpg is going to take a heavy hit from 3 mile stop start journeys in a city. Do you have figures from same journeys with a previous car? How did it compare to the manufacturers claimed economy figures? I would see what the car was delivering on a decent run. I had same engine, albeit manual so a couple of mpg more efficient, and was getting into the 40s on a mixed drive with a bit of dual carriageway driving. That should give you a baseline as to what the car is giving you. If that's also very low I'd get back to the dealer for repair, replacement, refund (research your consumer rights on Which of other like site)
 

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2020 Mazda3 Saloon in Soul Red Crystal.
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You would need proof that there is a fuel consumption problem which will be difficult to get. It’s a long shot but could you borrow an identical car to compare it against? I’m getting around 34 MPG in a 2020 saloon with the 178 BHP Skyactiv X engine. That’s short journeys in Sheffield. In better weather I get around 42 MPG for similar driving.
There are a lot of reasons for poor fuel consumption from a faulty thermostat (is the car getting to temperature in a reasonable time & staying there?) a faulty O2 sensor is a common cause as are faulty injectors.
A dyno (rolling road) fuel consumption diagnostic would be a good place to start. Taking a dyno diagnostic report to the seller would help your case considerably if it shows that you have a consumption issue. You’ve plenty of options for dyno centres in London.
It could be that there isn’t a problem with the car. The cost of a dyno report could be a price worth paying for peace of mind though.
 

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If you are never getting out of 2nd or 3rd gear. That's actually probably pretty good. Especially during the winter. 3 mile road trips will barely warm up the car during which time it's going to run rich to warm things up. So you'll need oil changes more often too. Try pressing the gas pedal no more than 1/3rd of the way down as you drive. Should help the mileage.
 

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Discussion Starter · #9 ·
Thanks guys - all very useful points of view and tips. In all honesty I have been (rather embarrassingly) doing more like 6x1 mile trips a day than 2x3 miles ones,,.so it might be all down to the impact of continuous stop and go, and driving until the engine has sufficiently heated up is. I will start ignoring continuous requests from the kids to give them a ride to school and keep an eye on the data on longer drives.
 

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2020 Mazda3 Saloon in Soul Red Crystal.
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Thanks guys - all very useful points of view and tips. In all honesty I have been (rather embarrassingly) doing more like 6x1 mile trips a day than 2x3 miles ones,,.so it might be all down to the impact of continuous stop and go, and driving until the engine has sufficiently heated up is. I will start ignoring continuous requests from the kids to give them a ride to school and keep an eye on the data on longer drives.
Your fuel consumption is actually good considering the amount of short trips you’re doing.
It isn’t good for your engine as It’s running constantly cold & using the richest fuel mixture possible most of the time. Over time it will use even more fuel. The injectors will gum up & you’ll get excessive carbon build up in the engine.
Have you considered an electric vehicle. It would suit your usage a lot better.
 

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Discussion Starter · #11 ·
Your fuel consumption is actually good considering the amount of short trips you’re doing.
It isn’t good for your engine as It’s running constantly cold & using the richest fuel mixture possible most of the time. Over time it will use even more fuel. The injectors will gum up & you’ll get excessive carbon build up in the engine.
Have you considered an electric vehicle. It would suit your usage a lot better.
Thanks again. I think you are absolutely right, but once every 2/3 months I drive to a small town 200 miles north. And once a year I do another holiday trip in the countryside or to France... And while I would possibly save money with an electric car for the test of the year and rental cars for these trips, overall petrol seemed the better choice. Perhaps in a couple of years I will see things differently
 

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Thanks again. I think you are absolutely right, but once every 2/3 months I drive to a small town 200 miles north. And once a year I do another holiday trip in the countryside or to France... And while I would possibly save money with an electric car for the test of the year and rental cars for these trips, overall petrol seemed the better choice. Perhaps in a couple of years I will see things differently
Most modern electric cars have a 200 mile + range so you’d only really need a rental car when you go to France or on longer trips. I’m not a fan of electrics, I think the future is hydrogen, but they have a lot fewer moving parts & can cope with short journeys without risk of critical component damage. I hope I don’t cause offence by giving an honest opinion but I think that at the moment you’re spending a fortune on fuel (& future maintenance) running a car that doesn’t suit your usage needs.
 

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Thanks guys - all very useful points of view and tips. In all honesty I have been (rather embarrassingly) doing more like 6x1 mile trips a day than 2x3 miles ones,,.so it might be all down to the impact of continuous stop and go, and driving until the engine has sufficiently heated up is. I will start ignoring continuous requests from the kids to give them a ride to school and keep an eye on the data on longer drives.
Check out the plug-in hybrids where they do up to 30 miles on the electric. It will probably make a bit more sense for your style of driving. Otherwise, those short-trips are killer on the fuel mileage. Overall though you aren't doing a lot of miles so it's really not a big deal.
 
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