Model Fuel Useage

[wass]

I was looking at the fuelly website at the real life fuel consumption figures for the auris, the prius the lexus CT and the yaris. I looked at the overall average figure for 2012 cars and I dont really understand them. As we all know, the Lexus CT and the Prius were designed as hybrids whereas the Auris and Yaris were designed as conventional car but have been "hybridised". Admittedly, the sample size for the Auris and Yaris figures isnt particularly large but what surprised me most of all was that the largest car is the most economical despite the smallest car actually having a smaller engine.

The government figures tell a different story to the fuelly figures. Does anyone know whether the drag coefficient of the Prius is responsible for it having the best real world fuel consumption of all the toyota group hybrids?

Perhaps prius drivers are the most light footed? Perhaps heavy footed drivers are attracted to the more recently released models?Any ideas?

[Opifex]

I haven't investigated this thought, but is it possible that a higher proportion of the Auris/Yaris owners have joined Fuelly in the last few months so their average shows winter results not the average for the year.

[johalareewi]

Does anyone know whether the drag coefficient of the Prius is responsible for it having the best real world fuel consumption of all the toyota group hybrids?

It would seem that way when comparing gen3 prius with gen1 hybrid auris. It might be true for newer auris and yaris.

With the fuelly figures. As well as cars starting in the winter taking an mpg hit and lowering the averages, you need to factor in the mpgs getting better as the car is run in.

[trevrobwhite]

I'm using a 2012 Prius+ with roof bars on it and 1 litre of fuel gets me near enough 10 miles. This is real usage around town, dual carrigeway and motorway. I have a family of 5 and the car gets well used full and with a single person in it when I use it for work.

[Hicardo]

Yep the most obvious reason for the discrepancy, given the same drivetrain, is that Prius owners are more "Eco warrior" than their Eco colleagues who choose a different vehicle.

So they drive more carefully, as you say with a lighter right foot, they "don't count" I suspect, tanks that have given them lower consumption figs etc etc

There's a Prius cab in my local rank that has an ave 49 mpg, and another with av 43 mpg. The latter guy floors it everywhere in power mode. However the first is probably more realistic for stop start daily use in all temps and weathers. My Prius av was 57mpg, over 3.5 years, but then I used another car for my runabout trips locally.

Another thing is that Fuelly is worldwide, and we know that consumption changes vastly in hotter temps. Some people on Fuelly have not posted consumptions in winter either, further distorting the figs

Conclusion - you need to carefully interpret average mpg claims especially from Prius owners. The Auris HSD IS just as economical in my hands, and apparently the Yaris even more efficient because of the weight saving and bang up to date HSD

[Ethanedwards]

Thanks this thread has cheered me up no end. Best I have got was 62 the last tank 58 and change. I thought I was doing terribly given the official figures. Turns out I'm a superstar!

Yaris HSD is a very small sample size and maybe it's skewed because I'm not using it as a city car but as a pounding up and down the A12 dual cabbageway at speed car.

[Parts-King]

The real world figure for my Auris HSD was 55 MPG on average

Kingo

[Hicardo]

Ethan...so your consumption sounds about right! Will go up a bit as the year goes on as well.

[johalareewi]

Yep the most obvious reason for the discrepancy, given the same drivetrain, is that Prius owners are more "Eco warrior" than their Eco colleagues who choose a different vehicle.

...they "don't count" I suspect, tanks that have given them lower consumption figs etc etc

Careful. You are almost calling all Prius owners tree huggers. (and liars )

Some of us have a prius to use less fuel because it has got so damn expensive. :arrgg-matey:

Some of us have a prius because there was only prius and we can't all afford to switch.

Another obvious discrepancy has already been mentioned. The gen3 prius and the 1.8 drivetrain were designed for each other. The auris wasn't. The drivetrain was added afterwards.

As you say, in normal use there isn't much difference between a prius and an auris in mpg terms and now you have a choice if you want to go Toyota hybrid. Not just with prius, auris or yaris, but also prius+ and plug in prius.

You may remember that Toyota did a competition last year to see who could get the highest mpg on a test drive. You could do it in a gen3 prius or a hybrid auris. The results were interesting in that the gen3 prius got slightly better mpg figures than the auris.

[jamesw]

Overall in the Auris I get around late 40's to low 50's to the gallon. This is me with a heavy foot sometimes and not others. Some people may view that as bad but for me who has it as a company car, I just fancied something that was an automatic and cheap on company car tax. Which this ticks the right options.

[Hicardo]

I argued (a little cheeklily maybe :D ) that some Prius figs perhaps were frigged a little because some people want to see their car remain the most economical. The drivetrain is the same, it doesn't matter if it was originally designed for the Auris or not. The Auris is slightly lighter i believe, and the Prius has slightly better drag coeff. So net-net it should come out about even, as the official figures claim. The Yaris is almost certainly more economical than a Prius

I dont think Mr T has stood still since the Gen3 Prius came out in 2009. My Auris HSD with the same drivetrain feels a little different to my old Prius. For instance i find the eco mode not as "dull" as the Prius eco mode. Whether they modified the ecu software between models is possible of course which may account for slight variations in consumption findings too. EV and Power mode behave the same.

[wass]

I have been looking further into why the Prius performs so well against other models in the Toyota range and the only thing I can put it down to is the drag co-efficient being so much better than the other vehicles allowing the Prius to slip through the air more easily than its counterparts who were designed with other things in mind.

The CT200 for example appears to have been designed with a slightly agressive styling. The Yaris and the Auris have been designed to reflect some of the characteristics or their competitors, the fiesta, the golf, the corsa, the micra etc.

Even taking into account that the newer models arent properly run in yet, there is still a performance gap between the Prius economy and that of its stable mates.

I was wondering how the prius might perform if the factory started to produce more aerodynamic tweaks such as modified mirror assemblies, undertrays, wheel covers and rear wheel arch fairings.

[Hicardo]

"Even taking into account that the newer models arent properly run in yet, there is still a performance gap between the Prius economy and that of its stable mates"

You state this as if its a fact....it isn't! For the reasons already pointed out

[wass]

"Even taking into account that the newer models arent properly run in yet, there is still a performance gap between the Prius economy and that of its stable mates"

You state this as if its a fact....it isn't! For the reasons already pointed out

By comparing models of similar ages and mileages first hand in a similar environment. I am lucky to be working with people who own the models I refer to. I am sure that your comment was meant in a helpful and constructive way. My comments are meant to be helpful and constructive too. I can make them without the use of exclamation marks. I am simply trying to find a reason for the generation 3 prius being bigger than other hybrid vehicles made by the same company and yet slightly more economical.

[Hicardo]

Sorry man, didn't mean to offend with exclamations! I have a tough time being kind and helpful. But getting better as i grow up

Maybe i've just got this all wrong, and what i've been failing to appreciate is that despite my own evidence to the contrary, my old Prius was actually more economical, and I just need to accept that

[Motif66]

I agree with Hicardo regarding the Auris It does feel lighter to drive in Eco mode than the Gen 3 Prius. In fact Eco mode on the Auris feels like standard mode on the Prius. I find it harder to hold in electric only mode, and these are on roads that I could quite easy manage with the Prius, It may be something to do with the fact you have more up front information on the Prius. eg. HUD.Hving said that if I get within 5% of the Prius I will be happy, Love the Auris.

[geoffatstanpit]

Last October I changed my Seat Leon TDI (CO2 146g/km Tax £125) for a new Yaris Hybrid (CO2 79g/km Tax zero) The Leon gave me 55mpg and was very nippy. So far the Yaris has done 53mpg despite being much less nippy (but perhaps more suited to one of my advanced years). The weights are much the same though the pig-ugly Yaris is clearly less aerodynamic.

So why did the Leon make all that extra CO2 while burning marginally less fuel?

Looking forward to the warmer weather when I hope to get the promised 81 mpg but I'm afraid to say I'm not holding my breath!

[timberwolf]

I'm pretty sure the wind doesn't care what the car looks like. :)

I was curious about the drag coefficient values, so I did a little searching:

the Seat Leon has a value between 0.33 and 0.3.

the Yaris Hybrid, despite being pug-ugly, has a value 0.286.

Diesel has more energy per litre than petrol and makes a little more CO2, although I'm guessing you didn't own the latest "eco" diesel engine, which probably accounts for more of the difference in the published figures*, the latest Seat Leon models appear to have a lower CO2 figure than your model.

http://www.acea.be/news/news_detail/what_are_the_main_differences_between_diesel_and_petrol/

Personally, I think too much emphasis is placed on the CO2 figure, and not enough on the other muck spewing out of the exhaust pipe, petrol being a bit less noxious than diesel on most measures.

[Hicardo]

Geoff, once the mileage has gone up a bit, and the warmer weather arrives, you shouldnt have to try too hard to make 10mpg better than the Leon, and you can have that warm toasty feeling that you're benefiting the green cause

Plus free road tax, and i would imagine, less insurance.

Actually think the Yaris hybrid looks pretty cool (from the front at least). Mind you, I think i look good in the mirror some mornings as well ..hehe