Am I Getting The Right Mpg?

[Opifex]

Hi,

At the start of December I bought a Prius T-Spirit, first registered in May 2010, from our local dealer, mainly in the hope of seeing the low fuel consumption that I had read about. I didn't believe that the figure claimed by Toyota was realistic but hoped that the 60mpg reported in the Which magazine was achievable. I have now done just over 600 miles in the car which has been a mixture of motorway, trunk road and queuing in the traffic going to the sales. The measured consumption has averaged only 49.1mpg which is well below what I was hoping for. The fuel consumption history display was, incidentally, showing 52.4mpg. I had thought perhaps the consumption was suffering from the cold weather but when I looked at the recorded consumption figures from new the highest that was shown was 53.7mpg. I was wondering whether the car is faulty but reading this and other forums it looks as though the lower 50s is about right. I would be interested to know if anyone manages to improve on this and how they do it.

[Phoenix999]

You have covered a very low mileage and I suggest that your mpg will improve slightly when the engine frees up in time and with a couple of thousand more miles on it

[Opifex]

A bit more info - the car was used by the dealer as a demonstration vehicle and loaned to staff, and has actually done 9000 miles.

[wizzlon]

I am getting a similar mpg- and it is down to the cold. In the summer I was getting into the 60s. Have a look at my fuelly figures. As the car "loosened up" over 3500 miles the mpg started to climb- until the cold set in!

[Hicardo]

Hi there, we get around 48-53mpg in winter depending on how far we go. My commute is 8 miles each way, so i dont think thats bad from a cold start each time. In summer on the same trip i get 55-57. In winter if i go for a couple of hours general spin on country / town roads, i get around 57mpg. In summer the same type of spin, i will get 62-64mpg. The warm up time IS everything, well that and the journey length / type. Hope that helps. Btw 95% of my driving is done in Eco mode.

[Grumpy Cabbie]

First thing I'd say is check your tyre pressures! Very very important in the Prius and can make a big difference. Often garages will adjust them to 30 psi but this is too low for the Prius - the correct pressures are shown inside the drivers door (depends on your tyre size and check it often).

Secondly, the car must have the correct oil (0w20) which it probably will still have in at 9,000 miles unless they serviced the car early for the sale. If they tried to skimp on the service by sticking 5w30 in (many Toyota dealers mistakenly believe this to be OK but it isn't - read previous posts) you will find a 5 mpg hit and will struggle to get over 60 mpg.

Thirdly, driving style for the Prius (or Auris HSD) takes a little getting used to to get the best out of it. By just holding back on the revs at certain times can stop the petrol engine firing up and thus help with economy etc. Practice but keep your eyes on the road too!

Four, the cold weather really hits the economy because heat is taken from the engine to heat the cabin just like a normal car, but this will cause the petrol engine to run longer than it would otherwise want to. Much of the economy gains in town are due to the engine being switched off at lights and low power requirements when you would use electric drive. In summer your economy will improve because the a/c is electrically driven and as such uses much less petrol than a normal car. Using a/c will still use more petrol than switching it off completely, but no where near as much as the mpg hit a normal car would take but opening windows is worse for mpgs. I leave my a/c on Auto at 20.5c. Also wet roads make a difference - surprisingly, due to the higher resistance on the tyres.

The way I look at it is that the Prius is a finely tuned economical car in the same way a Ferrari is a finely tuned performance car. You wouldn't use crap oil in a Ferrari and expect it to perform nor would you put cheap tyres on it with the wrong pressures. The same is true with the Prius but for mpg reasons.

You will see my average mpg for the last year is 49 mpg but this is mostly start stop heavy traffic driving. On a run out I can often get upto 70+ mpg and in fact even today I drove from Harrogate to Leeming Bar via a 50 mph road works section on the A1 and the 5 min trip average over the 30 min trip showed 48mpg, 75, 75, 80, 65, 50 mpg. The 2 x 75 and 1 x 80 mpg were on the 50 mph section of the motorway with the car fully warmed up, the first 48 mpg was warming the car up and the latter 50 mpg was after I overtook a few cars on an A road in Power mode (I couldn't help myself!).

So yes, you can get the mpg figures in practice.

[Jan&tone]

Opifex, listen to Grumpy! He's pretty much on the button as far as driving a gen3 Prius goes. As a cab driver he probably uses it more than anyone.

It really is down to how you drive the car, even in this weather on a 20 mile country road drive to work in this cold weather i still get 58 to 60 mpg with the a/c switched on (mine's at 19.5 though!)

[ian rooke]

Hi could the bad figures be down to the fact that as a dealers car on a test drive most people put the car in power to see how it performs, I know I did .

[Grumpy Cabbie]

Hi could the bad figures be down to the fact that as a dealers car on a test drive most people put the car in power to see how it performs, I know I did .

The car will default back to 'normal' mode once it is switched off. Or do you mean the car was hammered in test drives? That's possible I guess but you can't thrash a Prius in the same way you can a manual car - the car just won't let you over rev it. Anyhow mine's nearly at 40k hard miles and runs and drives like new and still gets good mpg's (like yesterday).

I really think the OP should get his tyre pressures checked first.

[peak_46]

I've now had the Auris HSD as a company car for just over two months and covered 6500 miles and averaged 49.3mpg. A high proportion of my driving is spent on motorways and dual carriageways where I try to stick at around 75mph. As I don't have to pay for the fuel I drive it as I would any other car and don't do the whole economy thing. I think as other people have mentioned the only way to get anything like mpg figures which could be seen as beneficial over other comparable vehicles fitted with medium sized diesels is to drive very very mindfully. Hybrids for me offer savings but only with quite considerable sacrfices to your normal driving style. If you expect to get an mpg return that may justify the extra invesment in a hybrid vehicle by driving normally you will most probably be rather disapointed. I'm struggling to see where the financial benefit is with hybrid technology and am very glad I didn't have to buy it.

[Grumpy Cabbie]

The argument for a hybrid was if you use it in town. The hybrids are automatic petrol cars that get 55 mpg at about 75 mph in my experience and about 50 mpg at 80 mph, both similar figures to a diesel car (which is at its most efficient at a constant speed).

In town or urban use the hybrid excels compared to diesels. I save thousands of pounds in fuel compared to a manual diesel car I had previously. Petrol cars don't clog up anywhere near as much as diesels do in town use either - I'm sure you've sat behind a mondeo taxi at the lights and been blasted with a cloud of black smoke when it set off!

The Prius (or Auris hsd) is a good all rounder. It can match a small diesel for mpg's on the motorway and beats pretty much everything else in urban driving AND that's with an auto transmission and petrol fuel (which is cheaper and cleaner). Add to this the tax benefits of hybrid cars and you're onto a winner.

But to get the very best mpg's out of it you do have to drive it steady, but isn't that true of any car?

[FourFourTwo]

A high proportion of my driving is spent on motorways and dual carriageways where I try to stick at around 75mph.

And there's your problem!

Read any article on achieving good fuel economy and you will see the same thing. - Driving over 60 mph drastically reduces your mpg! This is mainly due to wind resistance.

Studies report that every mph over 60mph results in a 1% reduction in mpg and that a driver can improve his mpg by as much as 25% by slowing down from 70mph to 55mph. It is important to understand that this applies to ANY car, whether petrol, diesel or hybrid. - It's just physics!

A hybrid is not something magic that you can thrash around at any speed and still achieve amazing economy, and neither is a diesel or anything else.

You do NOT have to drive mindfully or sacrifice your driving style to achieve good mpg in a hybrid, however, if you do drive mindfully, you can achieve outstanding mpg beyond that which you could achieve with a conventional vehicle.

[Cyker]

Yeah, 50-60mph is the sweetspot for maximal mpg on the motorway. Even 65 will see a noticeable drop in mpg.

I've been cruising around lots of 50mph zones on them M25 recently (!Removed! roadworks!) and my mpg has shot up!! I've covered just over 350 miles and I'm only 3 blocks down (That's about 15 litres of diesel!! )

And this is using V-Power diesel (Which generally gives 3-4mpg less than normal diesel!) in winter!!

I wub me Yaris :D

Now if only they made a turbo diesel HSD Yaris that was less than a tonne!! :D

[Grumpy Cabbie]

And this is using V-Power diesel (Which generally gives 3-4mpg less than normal diesel!) in winter!!

Oh no, you're gonna start me on the subject of which fuel to use!

Do we stick to 95 octane premium unleaded or put the more expensive 98 octane super unleaded in?

Normally I would have suggested using normal 95, but am I correct in understanding that this will start to contain 10% ethanol as of the new year and this will reduce the mpg's a little (if experience of US drivers is anything to go by). However, super unleaded 98 will continue to have upto 5% ethanol so will give more power AND more mpgs.

So, because of the mpg loss with 10% ethanol in petrol is it better to now use the more expensive 98 unleaded which should now give better mpgs?

[Cyker]

Ordinarily I'd say with petrol it makes no difference unless the engine is designed to take advantage of the higher octane rating so you're better off saving the money.

With diesel it is a different deal; They use a different ignition process so all diesel engines benefit from higher cetane ratings. (TBH I only use V-Power occasionally as a 'treat' to clean out the engine :))

Are they actually doing the 10% ethanol thing here then?

I've heard lots of bad things about it as you hit 10% or more ethanol from friends in the US, esp. people with older cars! Eating rubber seals, problems with higher water absorption, cold-starting problems, injector and sensor damage seem common complaints. And that's on top of the worse fuel economy!

It does raise the octane level tho' so I'm not sure how the blend will change if they're really putting it in regular petrol...

[johalareewi]

Hybrids for me offer savings but only with quite considerable sacrfices to your normal driving style. If you expect to get an mpg return that may justify the extra invesment in a hybrid vehicle by driving normally you will most probably be rather disapointed. I'm struggling to see where the financial benefit is with hybrid technology and am very glad I didn't have to buy it.

Depends but for major financial benefits just drive in London (congestion charge exempt) as a company vehicle (low benefit in kind tax).

Also compare the Prius with other automatic cars. A manual diesel can out mpg a Prius in certain circumstances (high speed long distance motorway driving for example) but the auto version won't, and it is probably more expensive to buy.

[Opifex]

Thanks for all the advice. I've not been out today so haven't been able to check the tyre pressures but will have a look tomorrow.

On the subject of fuel, I have occasionally used Shell V-Power in my old 2.3 turbo Saab and found that the car was definitely smoother and more willing but didn't show any significant difference in consumption.

I do a lot of driving in France and first came across SP95-E10 fuel about a year ago. I was a bit worried about using it but haven't found any problems and I understand that some brands (including Saab) have been able to use it without damage for about 15 years. I can't remember the exact wording, but the pumps have a notice saying something like SP95-E10 can be used in all cars built after 2000. SP95-E10 is being introduced slowly across the country and will eventually replace the SP95. At the moment there are still a lot of SP95 pumps, sometimes alongside the SP95-E10 pumps.

[Sagitar]

I put petrol in today and was disappointed to find I had only 47 m.p.g. for the last tankful. I thought of a lot of excuses, short journeys, cold weather and my recent adventures with the 12V Battery.

However, when I looked at the figures for this time last year, they were pretty much identical. So I guess it is just a winter phenomenon.

[Jan&tone]

I put petrol in today and was disappointed to find I had only 47 m.p.g. for the last tankful. I thought of a lot of excuses, short journeys, cold weather and my recent adventures with the 12V battery.

However, when I looked at the figures for this time last year, they were pretty much identical. So I guess it is just a winter phenomenon.

Indeed it is. In my gen2 last winter i was getting around 50-53 but in the summer before i swapped it that went up to 58-60, my gen3 is returning around 62 at the moment and i would expect that to go up when the weather warms up

[teamdirtydog]

Also compare the Prius with other automatic cars. A manual diesel can out mpg a Prius in certain circumstances (high speed long distance motorway driving for example) but the auto version won't, and it is probably more expensive to buy.

I drove our old Clio DCi to Germany and back last year and even flat out (actually foot to the floor) for about 4 hours on the autobahns and it still did about 45mpg! That was 3 people and all our luggage - I do miss the economy compared to our T-Sport :)

[Doesn'tExist]

A lot of it is about the way you drive it. Case in point, my wives had it last week and I was shocked to see 44.6mpg on the trip computer. I did the same journey for the first pattering this morning and got 86.7mpg. Then went on the m25 and m3 to farnborough doing whenever I can an indicated 80mph and I achieved an over journey of 64.9mpg.

Try and stay out of the little power zone, you don't go any slower. In stop start traffic switch to Eco mode if you have a heavy foot. And very gently try and pulse and glide. Trust me when you master it you actually make much more rapid progress than most and are not a slow prius prat.

[johalareewi]

.... my wives ....

[Doesn'tExist]

Typo on my *-%$ Android phone. Nothing exciting.