Tricks to get better MPG.

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Gray1969
Posts: 8
Joined: Tue Oct 01, 2019 8:04 am

Tricks to get better MPG.

Post by Gray1969 » Sat Oct 05, 2019 5:16 pm

Hi all,
Im at risk of making myself look a right idiot here, but here goes...........

After reading the somewhat negative comments on here regarding the MPG of the xc40, Ive become a bit obsessed with getting good MPG figures in my current car - Mazda 3 sport nav petrol manual.
I average 37 combined over the last 4 and half years, but today I've twice made 50mpg on a 25 mile country ride on single carriageway drive, by driving conservatively and coasting in neutral on downhill stretches.
So having never driven an automatic before (apart from our test-drive) and about to get the T4 automatic, question is can you do the same in an automatic? i.e - knock it into neutral on downhill stretches, then click it back into drive mode?

Sorry for my ignorance.

Cheers.
T4 Auto R design in Onyx black, 19" alloys, winter pack and convenience pack.


V50S60V70
Posts: 3
Joined: Sat Oct 05, 2019 5:36 pm

Re: Tricks to get better MPG.

Post by V50S60V70 » Sat Oct 05, 2019 5:49 pm

Not being the driver of an auto and not knowing what type of auto Volvo uses I can't say for sure, but throughout all my life I've been under the impression you cannot tow an automatic car without damaging the gearbox i.e. neutral on an auto is not like neutral on a manual.

But it doesn't really matter what the actual mechanics are because your theory is wrong.

Ever since electronics took over control of the throttle, you'll actually use MORE fuel when your car is coasting in neutral than you would if the car is in-gear. It's such a small difference it's not woth bothering about, but what happens is you put the car in to neutral and the engine goes in to idle mode, however there are occasions when in gear, your engine is either running below idle revs or if you don't touch the accelerator, fuel is cut off altogether.


USERof XC40
Posts: 34
Joined: Fri Oct 04, 2019 7:19 pm

Re: Tricks to get better MPG.

Post by USERof XC40 » Sat Oct 05, 2019 6:04 pm

In neutral your Mazda is idling i.e
using fuel.
Leaving in the correct gear coming downhill the likelihood is that the injection system of the Mazda will use no fuel at all.
I would recommend not to coast, you have less control - see rule123 Highway Code.


Ian333
Posts: 55
Joined: Fri May 11, 2018 4:35 pm

Re: Tricks to get better MPG.

Post by Ian333 » Sat Oct 05, 2019 6:17 pm

If you put my T5 auto in eco drive mode, it coasts all by itself if you remove your foot from the accelerator and are doing over about 35mph.

If Volvo implement this in their eco drive mode, I’m not sure how the above comments relate to this as I doubt Volvo would put something in eco mode that either uses more fuel or is illegal...?
Ordered T5 R-Design Pro with most of the bells and whistles in early May ‘18 and received delivery at end of Jan ‘19
Very Happy 😃... especially now it’s Polestarred


Gray1969
Posts: 8
Joined: Tue Oct 01, 2019 8:04 am

Re: Tricks to get better MPG.

Post by Gray1969 » Sun Oct 06, 2019 9:05 am

Thanks for the replies and advice.

The only thing I will say is, after starting to "coast" and knocking the car into neutral etc, Im suddenly getting these 50mpg+ figures for 25 mile journeys, ive also noticed the revs when in neutral got to about 500, which seems to be lower than keeping it in 6th gear with the foot off the accelerator?
But as has been said above, it may be different in an auto where electronics take control of the throttle?

Cheers.
T4 Auto R design in Onyx black, 19" alloys, winter pack and convenience pack.


USERof XC40
Posts: 34
Joined: Fri Oct 04, 2019 7:19 pm

Re: Tricks to get better MPG.

Post by USERof XC40 » Sun Oct 06, 2019 10:42 am

Just food for thought -
When in idle i.e. coasting, the revs you are seeing are produced by the idle i.e using fuel.

When in 6th gear the fuel consumption is, perhaps, zero and the (higher) revs you are seeing are the result of the wheels turning the gearbox and engine.

Not all revs are the result of fuel consumption.


Gray1969
Posts: 8
Joined: Tue Oct 01, 2019 8:04 am

Re: Tricks to get better MPG.

Post by Gray1969 » Sun Oct 06, 2019 1:27 pm

Cheers for that, you learn stuff every day.

I will do a similar journey and keep it out of neutral and see how the results compare.
T4 Auto R design in Onyx black, 19" alloys, winter pack and convenience pack.


AnotherXC40
Posts: 87
Joined: Fri May 03, 2019 9:55 pm

Re: Tricks to get better MPG.

Post by AnotherXC40 » Sun Oct 06, 2019 8:00 pm

I've got the T4 AWD Auto and have averaged 34 mpg to date with my best run of close to 100 miles getting 50 mpg. The coast function of the transmission disconnects the clutch to the engine and allows the drivetrain to coast down in the same way as with you putting your mazda into neutral, the difference however is the vehicle is intended to drive like this so the gradient the vehicle is experiencing along with signals from loss of traction through the wheels is monitored and breaking of each wheel can still be initiated in the same way as if your driving the car normally, this is not the case with your mazda in neutral. The highway code errs on the side of caution as the lack of control really refers to rear wheel drive vehicles when cornering, most modern cars are now front wheel drive and so the coasting side isn't such an issue. The non-hybrid transmissions are traditional 8 speed torque converter automatics sold by Asin-warner, while the new hybrid is a 7 speed DCT.

I drive in eco most of the time and the biggest benefit of the coast function is down long hills, as described the car is still idelling so fuel is being injected but at an absolute minimum - If I remember correctly its about 0.5L per 1 hour of idelling for a typical 2L engine. Most of the fuel burn in an ICE is from accelerating, if you can drive at a constant speed the vehicle is very efficient, so slowing down with engine breaking will cost you when you have to accelerate up again as you will have lost more speed and therefore will need to burn more fuel to rectify this difference, this will most likely be much more than the fuel consumed while coasting.

Planning ahead and adapting to driving conditions is the biggest impact you can have on fuel consumption.

Keeping your tyres at the recommended pressure (sometimes there is an eco pressure), removing unnecessary items from your car and keeping the windows and sunroof closed above 25mph are other things that negatively affect fuel consumption.

The downside of the eco setting is the reduction in air-conditioning/heating/demist. If it is raining I find the car struggles to keep the windscreen completely clear and mist can be an issue, as soon as you switch to another driving mode this solves this issue.
XC40 T4 AWD R Design, Xenium, Intellisafe Pro, Winter, Tow Bar, Thunder Grey


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