Mpg Inprovements On Yaris Hybrid

[LyWingGing]

hello all, I have a 2013 Yaris Hybrid, but the mpg I've been getting is around 46.7mpg, was wondering if the new 2015 yaris hybrid would perform better? I heard a a few months back they did some improvements on the Yaris hybrid, but I was wondering if anyone was getting better performance in terms on efficiency on the mpg because now I see toyota promoting the 2015 as 85.6mpg, thanks if anyone can help me with actual figures =]

[FROSTYBALLS]

Welcome to Toyota Owners Club.

Your profile shows you have a 2007 Aygo?

Toyota has to use the fuel consumption figures from the EU consumption tests in their advertising - this doesn't mean that in the real world one will actually achieve 85mpg.

[Cyker]

In other words, it's a big fat lie :P

I don't think the new one is significantly better than the old one for mpg, and certainly not enough for the extra money you'd need to drop on it!

We've had people getting everything from low 40's to mid-70's for mpg with the Yaris Hybrids.

It seems to vary a lot depending on journey type and temperature (The HSDs and diesels definitely get a nice mpg boost when the weather warms up!). People doing a mix of urban and A-road driving seem to do best from what I've read so far, whereas people in hillier areas seem to do worse.

The HSDs are much more sensitive than other engines for getting optimal mpg - Things that make a decent difference is the oil (0w20 seems to be a must to get the higher mpgs) and tyre pressures (higher tyre pressures or low rolling resistance tyres are highly recommended).

The engine takes longer to run in than other types because it has a lower duty cycle, so if it's quite a low mileage car, it may still be loosening up.

Lastly, driving style is very important; People that get the best mpg learn to abuse the fact that the HSDs can roll off-power for longer than any other engine type.

If you can leave a big enough buffer gap that you can roll through start-stop traffic and traffic lights without having to brake or accelerate as much, you save a load of fuel (I do this in my D4D and I routinely hit the high 50's/mid-60's )

[johalareewi]

A good place to go is fuelly.

http://www.fuelly.com/car/toyota/yaris?engineconfig_id=&bodystyleconfig_id=&submodel_id=62

[unclepoo]

Temperature and tyre pressures make a noticeable difference to mpg....now that the weather is getting milder you will see improvments.....so keep the tyres pumped up, and drive smooooooth.

[Grumpy Cabbie]

And don't try and fool the system by using EV mode tempting as it is. Deep cycling of the HV Battery by excessive use of EV mode or forcing the car to stay in electric longer than it would otherwise want will kill your mpgs.

It's a petrol car with electric assistance not an electric car. EV mode really should be used for reversing out of garages and showing off to your mates once in a while. And yes, it is fun to use it but there's a cost - low mpgs.

Oh, and B mode on the shift selector is NOT Brake mode to get more regen but an engine brake for going down long steep hills. That's really the only time it should be used.

[DarrenM]

And don't try and fool the system by using EV mode tempting as it is. Deep cycling of the HV battery by excessive use of EV mode or forcing the car to stay in electric longer than it would otherwise want will kill your mpgs.

It's a petrol car with electric assistance not an electric car. EV mode really should be used for reversing out of garages and showing off to your mates once in a while. And yes, it is fun to use it but there's a cost - low mpgs.

Oh, and B mode on the shift selector is NOT Brake mode to get more regen but an engine brake for going down long steep hills. That's really the only time it should be used.

Surely the excess energy from the B brake has to go somewhere? The charge needle swings further into the charge band indicating it's charging more, in the same way as when you're braking harder. Or does the amount of swing not indicate how much it's regenerating?

[Cyker]

Normally when you lift off, the HSDs only do a fairly light level of regen-braking so you can coast for longer (The most efficient way!).

I guess B-mode automatically engages maximum regen-braking when you lift off, whereas normally you'd have to apply a certain level of braking to get the full level of regen braking, but it will never regen more than that maximum level.

Any excess energy over that is dumped into the engine, making it spin faster.

[johalareewi]

Surely the excess energy from the B brake has to go somewhere?

The charge needle swings further into the charge band indicating it's charging more, in the same way as when you're braking harder.

Or does the amount of swing not indicate how much it's regenerating?

Imagine you are going down a long steep descent with your foot on the brakes:

In a normal car your brakes would overheat, so you engage a low gear and use the engine as an additional brake.

In a hybrid, regen braking charges up the HV Battery.

Eventually, the HV Battery will be full up with nowhere for the generated electricity to go.

So you engage B mode and some of the energy goes to the ICE (engine braking) instead of the generator.

It might be that B mode makes the regen braking more aggressive.

I can't say I have noticed it in the Prius, but on newer hybrids, who knows?

There is a lot of stuff on the internet about B mode.

This is a good place to start.

http://www.techno-fandom.org/~hobbit/cars/b-mode.html

At the end of the day, the job of B mode is to divert energy away from the generator to be dumped by the ICE.

FYI if the hybrid system detects that the HV Battery is full, it will automatically use the ICE as a brake.

[DarrenM]

Interesting reading thanks.

B mode a bit pointless then. Just to keep people who can't get used to not using engine braking happy.

[Sooty]

Not quite.

If you travel down a very long hill using normal braking and regen, when the HV gets full you will then be using the friction brakes and they will have a chance of overheating.

The B mode will act very much like an exhaust brake on a truck using the ICE as a braking method.

[MEP's Yaris GS]

B mode a bit pointless then.

Not at all, there are times when its essential, but think of it like Fog Lights, fitted, but only properly needs to be used once a year or so. I've only used it properly once on a hill decent over about 3 miles in Wales.

[DarrenM]

What about a rubbish hill? ;-)

[Grumpy Cabbie]

What about a rubbish hill? ;-)

Maxing out the HV Battery regularly will reduce it's life. There is one hill near me that will max out the Battery 8/8 bars and then some before you're half way down. The car absolutely revs the engine like crazy and does all sorts of other weird stuff to get rid of the excess charge as well. It also switches off regen causing you to use friction brakes only. You'd be amazed how much of the braking regen makes up. If you did that hill every day your HV Battery would be lucky to get to 100k miles.

Use the B mode to decend the hill and the HV battery will usually be 7/8 bars at the bottom or sometimes 8/8 but never totally and utterly full where the car cars weird stuff. Saves on your brake pads too.

So the B mode is very useful to people who live near hills, not just in the UK but Europe too.

[MEP's Yaris GS]

Maxing out the HV battery regularly will reduce it's life. There is one hill near me that will max out the battery 8/8 bars and then some before you're half way down.

Can't say I follow this, as although the HSI may show 8/8 bars, I very much doubt the HV is charged above its preset max % charge threshold, hence why the car is using engine braking etc.

Don't forget that the HSI meter is not true representation of the HVs real world SOC, more just what the car wants you to see.

[CPN]

I have yet to see my Yaris get to 8 bars on the head unit's display... It's never gone above 7, even on a really long journey...

[MEP's Yaris GS]

I have yet to see my Yaris get to 8 bars on the head unit's display... It's never gone above 7, even on a really long journey...

It won't unless going down a long down hill bit, as it leaves that top end free to accept some extra charge just incase you do go down a long hill.

Think of it like filling a glass with drink, you always leave that little bit from the top rather than brimming it, just incase you need the space to absorb fluid movement when picking the drink up.

[CPN]

Sounds like a fair analogy...

[PeteB]

Just like the top bar on the regular fuel gauge, the 8th bar on the HV Battery display covers a range of States of Charge.

I like to think of SoC as having two ranges, true, and the sub range that Toyota engineers decreed was available to use. On Gen 1 & 2, the latter was between about 40% & 80% (give or take 1%), I think Gen 3/Auris/Yaris is about the same. The gauge shows what's available within that window, so 4 bars is about 60% true. If the gauge ever went to empty, it would really be about 40%, and so on.

The 8th bar will light up at somewhere in the low 70s% (true) SoC, and max out at about 80% (when as far as the Hybrid system is concerned, the Battery is totally maxed out). In reality is has 20% of 'space' left.

It's these limits, along with careful charge/discharge management and temperature control that help to explain why Hybrid batteries last longer than a lot of people (including me when I bought my first one in 2002) thought they would.

On my 2002 Gen 1 Prius (which only had 4 larger bars on it's HV Battery display), I only saw it even light the top bar for the first time after 90,000 miles and nearly 5 years of driving it on a holiday in Scotland, where it maxed out at least once a day driving down very long steep hills. I can confirm B mode was very useful then. Also, when leveling out, as others have said it tries hard to use up that charge, and I got my first taste of what a true EV would feel like, as it used only electric power for quite brisk acceleration up to 60 mph until it used up the excess.

[johalareewi]

B mode a bit pointless then.

B mode is very useful in the snow and as GC has said, if you go down big hills a lot.

But for day to driving you probably won't use it.

[kithmo]

I have yet to see my Yaris get to 8 bars on the head unit's display... It's never gone above 7, even on a really long journey...

It won't unless going down a long down hill bit, as it leaves that top end free to accept some extra charge just incase you do go down a long hill.

Think of it like filling a glass with drink, you always leave that little bit from the top rather than brimming it, just incase you need the space to absorb fluid movement when picking the drink up.

...so when the Battery is at 4 bars, is it half empty or half full ?

[Grumpy Cabbie]

Just like the top bar on the regular fuel gauge, the 8th bar on the HV battery display covers a range of States of Charge.

I like to think of SoC as having two ranges, true, and the sub range that Toyota engineers decreed was available to use. On Gen 1 & 2, the latter was between about 40% & 80% (give or take 1%), I think Gen 3/Auris/Yaris is about the same. The gauge shows what's available within that window, so 4 bars is about 60% true. If the gauge ever went to empty, it would really be about 40%, and so on.

The 8th bar will light up at somewhere in the low 70s% (true) SoC, and max out at about 80% (when as far as the Hybrid system is concerned, the battery is totally maxed out). In reality is has 20% of 'space' left.

It's these limits, along with careful charge/discharge management and temperature control that help to explain why Hybrid batteries last longer than a lot of people (including me when I bought my first one in 2002) thought they would.

On my 2002 Gen 1 Prius (which only had 4 larger bars on it's HV battery display), I only saw it even light the top bar for the first time after 90,000 miles and nearly 5 years of driving it on a holiday in Scotland, where it maxed out at least once a day driving down very long steep hills. I can confirm B mode was very useful then. Also, when leveling out, as others have said it tries hard to use up that charge, and I got my first taste of what a true EV would feel like, as it used only electric power for quite brisk acceleration up to 60 mph until it used up the excess.

If this picture works it should confirm what you've just said;

It's the true percentage state of charge of the Battery against the displayed bars.

[PeteB]

Thanks, that's a great graphic.

[DarrenM]

So it varies how much it tries to stay on EV for? Mine seems to just be always on EV below 45 MPH as long as the eco needle is below half way. As soon as the needle touches half way (from hitting a bump in the road, jarring my foot etc) it'll turn the ICE on. Only done 900 miles though so perhaps it'll learn and adapt more?

[Grumpy Cabbie]

It does and it will and it's a very grey area. The car adjusts to all sorts of other sources; outside temp, coolant temp, engine temp, Battery temp, cabin temp, draw on the a/c, what state of charge the Battery is etc. If it's low the car will err more on trying to top the Battery up and will switch the engine on quicker or earlier. If the battery is totally full as in 8/8 bars at the top end of that scale the car will run as if in EV mode right upto 45 mph (EV mode is normally 31 mph) with much quicker acceleration than the restricted EV mode normally offers and much more than the small amount of electric only drive you can 'force' by gentle acceleration. This is because the car desperately tries to burn off that excess charge. Once the charge reduces the car slowly starts to return to normal. You need a long, steep and fast hill for this to happen. I know of only one near me that it's guaranteed to occur on and I live in a hilly part of the world.

You'll also get a slight insight into similar workings when you try and engage EV mode by pressing the button. When the car is cold (relatively) EV mode will kick out at 20 mph. When the car, and importantly the HV battery is warmed up, the car will allow EV mode to be selected upto 31 mph. But if the battery gets too warm or is used too often or the a/c is on too high, it won't allow you to select EV mode full stop.

It's a very well designed computer program with many many variables, hence why it is said that one should leave the car to decide what is best for economy as you can't fool it long term.