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Are Manufacturers mpg figures possible?

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Simple question - does the B mode help or hinder economy?

Cheers

 

Tony B

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Hinder!

While you're pressing the accelerator, B mode makes no difference to anything.

When you lift off or brake, the petrol engine is made to run with no fuel (I think the values are heavily retarded (or maybe advanced)) to maximise pumping compression which gives some braking effect.  Because some of the braking is being done this way, there is less energy available for regeneration via the motor/generator so that's less energy put into the HV Battery and therefore a little more work done by the petrol engine that otherwise would have been done using energy from the HV Battery.

It didn't help, when the first Prius came out in the UK in 2000 that the handbook used the phrase "more aggressive regenerative braking" - this led many (including some Toyota people) to believe B mode meant extra saving.

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Posted (edited)

I don't completely agree with you.

With our Yaris, if you watch the power meter, the charging is high in B mode.  Brake as well, and you get maximum charging as indicated on the meter.

If you controlled the car to the same extent on the same hill at the same speed, just braking alone, it's the same as in B mode.

You need to live in a hilly area to test this out of course, and I've experimented endlessly. 😀

Mick.

Edited by Mick F
The forum didn't like re tard

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"B" mode is just like using low gears to help reduce brake application on long down hill runs.

It really only has a use in the above situations as it helps reduce brake "fade" from over use of the brakes causing them to over heat and fade.

"B" mode is just about no use during normal flat-ish driving.

 

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there is another use of B mode when you are going downhill:

If your Battery is full or close too full and you still need to drive downhill simply use B mode so you do not overcharge Battery, but there are probably safety feautres preventing over charging battery 

 

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The computer looks after it all, so you don't need to. No need to worry at all.

Braking gently, the regen alone does the braking.  Brake harder, and it's regen plus brakes.

If the Battery is completely full, the only braking you have are the actual brakes like a normal car.  Regen won't generate if it doesn't need to.

Mick.

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PS:

The Battery indicator could show all eight bars, but that doesn't mean the Battery is completely FULL.

Mick.

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Thanks to all on your replies on the B mode.

Like many of the hybrid "tricks" it seems to be drive steadily in any mode and the computer will do the thinking.

In the plug-in I am finding the same happens - just keep topping up from mains as and when and drive as steadily you can and the car seems to deliver great economy - 230 miles over 3 days at 193 mpg indicated - helped by a couple of free top-ups in York.

One frustration I was having was being unable to use cruise control in B mode thinking it was regenerating a lot more Battery charge.

Cheers

Tony B

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One tip I picked up on this forum re the use of B mode (apart from going down hills) was to engage it when driving slowly on ice/packed snow. Just to help keep the car steady with a slight braking effect drag. Not used the technique yet, think we only had very light snow in the Chester area this last winter. 

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Very good point Joe.

I did use "B" mode for that very reason last winter when we had the sudden snow in Stoke.

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If it snows here, we can't get out!

Long steep north-facing rural drive, and even if there's just a heavy frost, we can't get out!  Bad enough on foot!!!!

If it snows after we've left, we can't get home, so park down the road at the local pub.  Every cloud has a silver lining! 😀

Luckily, being in Cornwall, bad snow and bad winters are few and far between.

Mick.

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B mode is only there because of construction and use regulations and IMO, ECO and power modes are there for those who can't control their right foot. :rolleyes:

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Original question: are manufacturers figures possible? Answer: yes.....but the conditions must be ideal to equal ideal figures. In every case, I have been able to beat manufacturers figures for every vehicle I owned this century. The concentration required is approx twice the intensity of the normal drive. I am of course referring to real fuel consumption and not the riduiculously inaccurate figures produced by on board (self promoting propaganda machines) computers. Everything has to be just right. Route, traffic density, ambient weather, tyre pressures.....surprisingly great amount of variables come into play. I have improved upon manufacturers figures by doing things which the manufacturers aren't allowed to do to derive their figures....like slip streaming the biggest lorry I can find at  around 45 mph!

It is possible but it can annoy other road users and sends passengers to sleep with the boredom of a single sided conversation.

Manufacturers figures are sales propaganda best case scenarios

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answer to the original question  was up to 95 mpg before a long hill IMG_0721.JPG?_uid=519866030&name=IMG_0721.JPG&hid=1.2&ids=169729410956529503&no_disposition=y&exif_rotate=y

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Copied from my original post. We had been on hol in Gloucester, decided not to come home using mways so Gloucester-Tewskbury-Worcester-Kidderminster-Telford-Chester area.

Then coming home on Saturday 22nd June116 miles (remember no MWay so shorter) 88mpg, pretty amazed. However, if you look bottom right of screen, it shows the last 50 miles (we stopped in Telford for a comfort break) it shows 96.5 mpg

The 88mpg was over 116 miles from Gloucester to Telford.  We stopped for a short break, then completed 50 miles from Telford to home near Chester at 96.5 mpg.

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Why is the Prius far more economical than the Yaris Hybrid?

Battery size? Better engine? Both? ............. or is it vehicle shape?  Or all three?

Mick.

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Sorry power failure screwed up image hope this works as you can see you can get to manufactures figures but things have to be perfect this was a trip round the M25 two passengers and luggage so could be slightly improved upon  

IMG_0721.jpg

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3 hours ago, Mick F said:

Why is the Prius far more economical than the Yaris Hybrid?

Battery size? Better engine? Both? ............. or is it vehicle shape?  Or all three?

Mick.

Dont know the answer but, the Prius Gen4 Battery is different to the gen3. I getting at approx 10mpg more from g4. So maybe the Yaris Battery is more g3 then g4. It will be smaller I would think anyway, to fit in.

Maybe the engine design is different, I know the g3/g4 is an Atkinson cycle, which may give better mpg.

Shape - definitely a factor. The coefficient of friction for the g4 with 15” wheels (mine) is .24, just look at its shape - it’s designed to cut thro the air, and not just its frontal design, the whole lot front to back and underneath. The Prius is closer to the ground too, even g4 lower then g3.

so,yes, probably all three in one way or another. The Prius is such a pleasure to drive. Go and have a test drive, preferably of a g4.

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1 hour ago, ian rooke said:

Sorry power failure screwed up image hope this works as you can see you can get to manufactures figures but things have to be perfect this was a trip round the M25 two passengers and luggage so could be slightly improved upon  

IMG_0721.jpg

What was your question about  “before a long hill”

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Sorry i was referring to the question "are manufactures  MPG figures possible" on occasion they are as you can see, the reading was at 95 mpg before I hit a long hill just before my destination   

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Understand now. Thanks

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13 hours ago, Mick F said:

Why is the Prius far more economical than the Yaris Hybrid?

Battery size? Better engine? Both? ............. or is it vehicle shape?  Or all three?

Mick.

All three, I would expect. I remember seeing the Battery specs somewhere, and the Yaris Battery is tiny by comparison to the Prius. It can't run the car engine-off at high speeds which is a big advantage for the Gen 4. The Yaris engine has less power, which might mean it has to be worked harder more often. It certainly felt like that when I tried one years ago, although that was far from scientific. And the drag coefficient is somewhere around 0.29 which is far from being a housebrick, but still notably less efficient than the Prius.

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14 hours ago, Mick F said:

Why is the Prius far more economical than the Yaris Hybrid?

Battery size? Better engine? Both? ............. or is it vehicle shape?  Or all three?

Mick.

Aerodynamic drag minimisation. The Yaris is lighter and smaller but not as slippery as a Prius.

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Also the Prius has different hybrid software. For example I don’t believe the Yaris or Auris can go above 40mph on electric only whereas the Prius and Corolla can switch its engine off

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The other day, in the new Corolla, I was doing 65 MPH just feathering the throttle, the car was holding in EV, the Auris would never do that, hence why the Auris would do 58 MPG and this Corolla is on 72 MPG, amazing difference and a much better car 

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