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Fuel Efficient Toyota Car - Prius

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So far, so good, Prius is the most current efficient baby I've had. Or, is there a Toyota model that beats this?

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The best I have achieved in my Gen4 Prius is shown on the dash photo below.  96.5mpg over 50.5 miles, a journey from Telford to Chester area. It was a hot day last June, the engine was already hot when we started that 50 mile run, we had stopped for a comfort break in Telford as part of our journey home from Gloucester.

93243417-2F6C-4FE4-AB8C-3CBA7805B1D7.jpeg

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The plugin prius can do better because you can start with a full HV charge.

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3 hours ago, johalareewi said:

The plugin prius can do better because you can start with a full HV charge.

We don't have one, or even a plugin Yaris, but living down in a deep valley, we wouldn't need to plug it in at all.

I wish our Hybrid Yaris had a bigger Battery

Mick.

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I have a niggle about the telemetrics presented by Toyota.  It is very impressive, in my Corolla, to be presented with driving efficiency, my braking and acceleration, average speed, distance travelled, journey time, fuel consumption etc but where do they source the parameters for the analysis?

My niggle is based on my fuel consumption being consistently higher than the official consumption by a small margin.

My speedometer display is consistently 10% over reading measured both on an independent GPS and road side speed displays.  However the journey display is obviously derived from the SatNav and the time is either direct from the Satnav or derived from it.  The first question is where is the distance derived from?  Is it from the speedometer or the SatNav?  On all cars where the mileage displayed is derived from the indicated speed their total distance displayed will be 10% too great unless that 10% speed margin is applied after the distance measured (tyre wear and pressure differences ignored).  The other unknown using the car systems is the accuracy of fuel consumption measurement.

One way to compare fuel consumption would be to do a full to full fuel consumption against and SatNav route with actual mileage.

So, where do they source the parameters for the analysis?

 

*for comparison my Corolla records 72 mpg down hill and 68 mpg up hill.  This is for a 15 mile journey up and down the A1 with cruise control set at 65 indicated 60 true and an average speed of 31 mph.  The EV distance varies hence the different consumptions.

 

 

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I raised this issue about the speedo over-reading in our Yaris.  10% is about right.  Been driving and owning cars since I was teenager and I'm 67 this autumn.  The Yaris is the worst car by FAR in the speedo being wrong.  I've owned 18? different cars through the ages and this is my first Toyota.

Are all Toyotas as bad as 10% high?  If so, why are they so bad?

The odometer is spot on though, as compared to GPS, and as compared to the marker-posts on the dual carriageways.  We don't have satnav, so my GPS info is from a handheld Garmin Montana.  Very accurate.

Why the speed is 10% high and the distance spot on, seems a mystery to me.  Why these two systems can't talk to each other completely baffles me.

Mick.

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European law states that all speedometers MUST read a percentage plus 1-2 mph above actual speed.

Odometers Must be accurate for legal and insurance reasons.

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EU legislation requires that the indicated speed must not be more than 110 percent of the true speed plus 4 km/h at specified test speeds. For example, at 80 km/h, the indicated speed must be no more than 92 km/h.

UK legislation from 1986 differs slightly in that for all actual speeds between 25mph and 70mph (or the vehicle's maximum speed if lower than this), the indicated speed must not exceed 110% of the actual speed, plus 6.25mph. For example, if the vehicle is actually travelling at 50 mph, the speedometer must not show more than 61.25 mph or less than 50 mph.

Both require that speedometers should never under read.

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I'm in no doubt, and in full knowledge, of the UK laws on this matter.

My point - as always - is why does our Yaris read 10% high when ALL the other cars I've owned and driven, have been much better than 10%.

Since first getting hand-held Garmin devices and bicycle related ones, I've checked our cars.  Also, before that, I modified a Mini and changed the diff as well.  I had a variety of speedo drives for the Mini/Maxi/1100 series and was able to get one which was just about correct.  I timed and measured whilst driving on the motorways counting the 200mtr marker posts to prove my speedo was ok and within the law.

Since then, I've always checked the speedos and odometers of the cars.

Our Toyota Yaris is WAY WAY higher reading than ANY car I've owned.

Why so high?

I've got to the point now of habitually driving at 32mph in the 30 limits, and 43 MPH in 40 limits knowing I'm within the law.

I know full well that when I'm driving long distances on the motorways or dual carriageways that if I drive at an indicated 70mph, I'm actually doing 64mph.  I've got to get up to 75 to do 70mph.

Remember, the odometer is spot on.

Mick.

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As you said, this has been discussed previously. Please return to the topic subject - Fuel efficient Toyota car - Prius.

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I have a niggle about the telemetrics presented by Toyota.  It is very impressive, in my Corolla, to be presented with driving efficiency, my braking and acceleration, average speed, distance travelled, journey time, fuel consumption etc but where do they source the parameters for the analysis?

My niggle is based on my fuel consumption being consistently higher than the official consumption by a small margin.

My speedometer display is consistently 10% over reading measured both on an independent GPS and road side speed displays.  However the journey display is obviously derived from the SatNav and the time is either direct from the Satnav or derived from it.  The first question is where is the distance derived from?  Is it from the speedometer or the SatNav?  On all cars where the mileage displayed is derived from the indicated speed their total distance displayed will be 10% too great unless that 10% speed margin is applied after the distance measured (tyre wear and pressure differences ignored).  The other unknown using the car systems is the accuracy of fuel consumption measurement.

One way to compare fuel consumption would be to do a full to full fuel consumption against and SatNav route with actual mileage.

So, where do they source the parameters for the analysis?

 

*for comparison my Corolla records 72 mpg down hill and 68 mpg up hill.  This is for a 15 mile journey up and down the A1 with cruise control set at 65 indicated 60 true and an average speed of 31 mph.  The EV distance varies hence the different consumptions.

 

 

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Frosty, thank you and that cleared up the speedo issue which suggests that the computer mpg displays are accurate.  Speedo accuracy is also relevant, Prius or other as a stated MPG should be caveated by speed for obvious reasons.

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10 hours ago, Mick F said:

Are all Toyotas as bad as 10% high?  If so, why are they so bad?

I don't believe it's all Toyotas - possibly just the hybrids. Our old Corolla 1.6 wasn't too bad. However, our two Priuses and Auris HSD have all been around that 10% over.

My conspiracy theory, supported by absolutely no evidence whatsoever, is that this is a deliberate cheat intended to improve the fuel economy of Toyota hybrid cars. If the speedo over-reads, most people will just follow what it says and drive slower. Driving more slowly, in many situations, will lead to better fuel consumption.

On 8/1/2020 at 6:40 PM, Catlover said:

96.5mpg over 50.5 miles

Fair play Joe, that's pretty good for a Gen 4 ordinaire. Of course, my own screen currently shows 199.9mpg averaged across hundreds of miles travelled in the months of June and July... but then I'm a cheater with a plug!

The Gen2 PHV must surely win the 'most efficient Toyota' award? I'm not counting the weirdo Mirai, as I don't live in Swindon.

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13 hours ago, Ten Ninety said:

I don't believe it's all Toyotas - possibly just the hybrids. Our old Corolla 1.6 wasn't too bad. However, our two Priuses and Auris HSD have all been around that 10% over.

My conspiracy theory, supported by absolutely no evidence whatsoever, is that this is a deliberate cheat intended to improve the fuel economy of Toyota hybrid cars. If the speedo over-reads, most people will just follow what it says and drive slower. Driving more slowly, in many situations, will lead to better fuel consumption.

Occam's Razor applies here too, eh?

I agree with you, keep the speed lower, and you get better fuel consumption is a given fact. Toyota deliberately making the speedo reed 10% high so you drive slower is a supposition borne out of experience of what car-makers do to fool the public.

Mick.

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On 8/3/2020 at 11:57 AM, Roy124 said:

I have a niggle about the telemetrics presented by Toyota.  It is very impressive, in my Corolla, to be presented with driving efficiency, my braking and acceleration, average speed, distance travelled, journey time, fuel consumption etc but where do they source the parameters for the analysis?

My niggle is based on my fuel consumption being consistently higher than the official consumption by a small margin.

My speedometer display is consistently 10% over reading measured both on an independent GPS and road side speed displays.  However the journey display is obviously derived from the SatNav and the time is either direct from the Satnav or derived from it.  The first question is where is the distance derived from?  Is it from the speedometer or the SatNav?  On all cars where the mileage displayed is derived from the indicated speed their total distance displayed will be 10% too great unless that 10% speed margin is applied after the distance measured (tyre wear and pressure differences ignored).  The other unknown using the car systems is the accuracy of fuel consumption measurement.

One way to compare fuel consumption would be to do a full to full fuel consumption against and SatNav route with actual mileage.

So, where do they source the parameters for the analysis?

The car knows the real speed, well as accurately as it can be measured from the wheels - you can get this from the OBD-II port. I think the recorded distance travelled is fairly accurate because of this.

The problem with trip computer fuel consumption is that cars do not generally measure fuel flow directly, it's usually guessed based on airflow and other metrics, because it's cheaper :)
All cars with electronic fuel injection have a mass air flow meter, but a fuel flow meter isn't necessary.

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On 8/4/2020 at 7:50 PM, Mick F said:

Toyota deliberately making the speedo reed 10% high so you drive slower is a supposition borne out of experience of what car-makers do to fool the public.

I don't believe there is any conspiracy on Toyota's part neither is it a bid to trick the public but it is more related to the convoluted UK regulations than anything else.  Prius in other markets are calibrated differently again according to local regulations.  In NZ and Aust, for example, the speedo displays the vehicle's speed (which is accurate as also measured both on an independent GPS and road side speed displays) plus 2 km/h (1.2 mph) across the board, not a percentage.  This covers new tyre vs old tyre and ensures the vehicle is not going faster than displayed.

Fuel economy calculations are based on the true speeds and distanced, not the adjusted display speeds and the observed inaccuracy will be just as outlined by Quantum Fireball.

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.......... so why are they so different in UK?  Why are Toyota Hybrid speedos reading higher than other makes/models  ............ or do they?

I understand the law in UK, and also understand that other countries have different laws .................. but they all say the speedo mustn't read below the real speed, so why not have them plus one or two MPH above rather than 10% high?

In this technological day and age, it isn't that difficult to get it right.

I'm a regular poster on a completely different forum on a completely different subject, but I'm going to ask them in their cars to check their speedos against satnav/GPS and report back.  Hopefully, we'll get an across the board set of figures and we may see which make of car is worse.

Mick.

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It's the EU legislation (as mentioned by Frostyballs) rather than specifically the UK that allows this. I've seen this discussion elsewhere that it varies with manufacturers, e.g. BMW speedos are closer to being accurate. My previous Peugeot seemed to overread by about 5% or so. I get the impression most manufacturers err on the side of caution than aim for accuracy. I don't know about the Prius but I know some can be adjusted with the dealer diagnostic equipment (usually to adjust for different wheel size).

It's fun to pass speed cameras at an indicated 108 km/h in a 100 zone, much to the dismay of the passengers :)

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Yeah, my previous VW group cars were more accurate - about +5% ... similar to that from QuantumFireball above.

Believe the speedo in a Toyota and you'll be at least 5mph under the posted limit on major roads which can wind up less patient road users. The Road Sign Assist seems to use the speedo number rather than the actual speed, which makes it pretty much pointless unless set to the maximum +5mph on the Auris. I'd rather it was calibrated more accurately than having to do mental arithmetic to compensate when road conditions are good.

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14 hours ago, MagicBoy said:

I'd rather it was calibrated more accurately than having to do mental arithmetic to compensate when road conditions are good.

I agree, but at least the Prius's 10% error makes that calculation easy – 22, 33, 44, 55, 66, and 77 mph when you see 20, 30, 40, 50, 60, and 70 mph signs, respectively.

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17 hours ago, Joseph D said:

I don't believe there is any conspiracy on Toyota's part neither is it a bid to trick the public but it is more related to the convoluted UK regulations than anything else.

The EU regulations might allow and encourage a significant over-read, but they don't explain why Toyota hybrids seem to be so bad. As already pointed out, all UK cars over-read, but our hybrids appear to do so much more than others. This seems unlikely to be accidental, although it's not necessarily a bad 'trick' to play given that the improvements in fuel economy are real enough.

The NZ/AU system sounds much better. I presume a similar approach applies in the USA, where I have driven a wide range of vehicles and the speedo in every one has been almost spot-on compared to GPS, even at 80+mph. Mind you, they take a far more enlightened approach to speed over there. Driving below the posted limit in some states is considered antisocial!

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I use Fuelly website, so I can compare the data on the dash to the website.
So my mpg is between 3 and 5 mpg, lower than what’s shown on the dashboard.

Since I can get similar economy as an aygo. Without driving cautiously and still keeping up with traffic.

Sadly the next car won’t be a Toyota, I plan on a electric car next.


Sent from my iPhone using Tapatalk

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8 hours ago, Joseph D said:

I agree, but at least the Prius's 10% error makes that calculation easy – 22, 33, 44, 55, 66, and 77 mph when you see 20, 30, 40, 50, 60, and 70 mph signs, respectively.

With my 2012 Plug-in on 15" wheels it's more like 8%.

6 hours ago, Ten Ninety said:

I presume a similar approach applies in the USA, where I have driven a wide range of vehicles and the speedo in every one has been almost spot-on compared to GPS, even at 80+mph. Mind you, they take a far more enlightened approach to speed over there. Driving below the posted limit in some states is considered antisocial!

When I drove in the US, I assumed the speedos over-read the same as here so always went about 5 MPH over the limit. I didn't get any tickets though :)

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Our Prius Plug In 2015 (gen 1) with 15” wheels is more like 8% too (as QuantumFireball said) , when I test with my android GPS app ( don’t know how truthworthy it tealy is , though)

Our Prius+ 2017 with 16” wheels is more like 8% too (measured with the same GPS) but…

When I tested a Prius Plug In 2017 with 15” wheels it was more like 7% (same GPS)

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