Real World MPG Figures

Stuart Aspey · January 15, 2017

Hi all. I picked up my 13 plate IS300H Premium on Jan 5th and am finding that getting above 42 MPG seems difficult on my commute and work travels. How is everyone else getting on?

Alan Partridges Left Glove · January 15, 2017

I'm now getting around 45-46.

I came from Volvo D4 cloud making machine so I automatically drove the IS in the same manor I would the Volvo and was getting the high 30's on my commute.

Since then I've changed my driving style from "Mario Karts" to a more cruising style and I don't mean "Driving Miss Daisy" style.

I've learnt how and when the Eco kicks in and how to get a better result from my tank.

I'm sure yours will improve but above all, enjoy the car, its quietness, it's comfort, and that lovely feeling when you put it in Sport mode at the lights and watch those behind you flounder with gears as you're up to 30mph in an almost silent blink of the eye.

Drive careful out there as there's still some BMW drivers around. [emoji6]

Stuart Aspey · January 15, 2017

Lol. Yeah, I came from the 2.0l is200, so no matter how soft a right foot I had, mpg didn't change. I need to find an inner calm and listen to the car.

malcolmw · January 15, 2017

My other half is getting about 46 - 47mpg overall in her 2016 IS300h. She does typical local journeys of 5 - 8 miles each.

BigChange · January 15, 2017

Here's the result of 1 year and 9060 miles in a 2015 is300h on a fill to fill basis - overall 47.44; best 53.7; worst 39.0; winter generally in low 40s and summer generally in low 50s. This on a mix of roads - city, town, country, mway and Continental autoroutes. Car mpg indicator is around 10% too high ie car 56 = real world 51. The car is really happiest pootling along at below 60 mph without too much stop/start acceleration. Not so happy mpg-wise with high speed runs on French autoroutes ! But it's a comfortable safe ride and without backache after a long trip so lots to be happy about.!!

twozero3 · January 15, 2017

I seem to be over achieving.

Currently indicated fuel consumption for my 20 mile round trip commute, which constitutes the majority of my driving is 50mpg. In summer I'll see 56-58mpg.

Back in October I drove 208 miles from home to Heathrow airport that single journey indicated 61mpg. My best ever for a single journey of any length (93miles) was 63mpg a fair part of that was on the M6 speed restricted to 50mph

All done with a smooth driving style in normal mode. Just to add another angle to it, I only ever use "premium" petrol, Tesco momentum 99, BP Ultimate, Shell V Power etc.

Slickk · January 16, 2017

Computer showing an indicated 31.8 mpg, which was reset after a service roughly 1 month ago. Brimmed the tank with fuel and set about my usual driving, which really isn't much. I currently drive approximately 20 miles a day - mostly local city/town driving and a very short motorway stint to and from work.

Car is always in Sport mode but that doesn't mean that I 'floor' the throttle pedal or brake aggressively

Stuart Aspey · January 16, 2017

TwoZero3, I wonder whether the premium is heavier than others? or maybe there is an indication that, at 54000 miles, maybe there is a Battery issue . . . . . I did a nonstop run to Swindon on Sunday, from South Wales. Best I could get was 42.6. this was with the cruise control on and trying to keep acceleration as smooth as possible. admittedly, the cruise control was at 71mph, It was wet and I did have the kids with me.

But the kit and comfort is amazing. I'm just wondering whether there could be some gremlins in the works

Stuart Aspey · January 16, 2017

YAY! My post signature has returned . . . . .

^ 60,000 miles of driving the same route with my 2.0 litre Sportcross and I'm getting metter than the official figures. . . . was hoping for the same with the Hybrid, to be honest . . .

IS300Hdriver · January 16, 2017

Might be worth running a couple of tanks of premium fuel through it and see how it gets on, usual things go without saying such as checking oil level and tyre pressures along with wheel alignment if you notice it pulling to one side at all. A few hard brake applications from high speed (obviously checking behind that it's safe to do so first) may clean the brakes a bit if they are possibly dragging.

As for everyday driving below 40mph, I keep it in normal as get too frustrated with just how hard you have to press the pedal to get decent progress out of Eco mode. Best technique I've found so far is to accelerate sufficiently with engine only (ideally low enough on the eco gauge as possible to charge the Battery at the same time) then foot off at speed and back on gently to run in EV mode on level roads for as long as possible. Coast as much as possible as this is the most efficient way to recharge the hybrid Battery (until reaching crawling pace when it then uses energy to keep the car moving along), brake gently to keep the needle as high as possible in the charge range but only when safe to do so.

There's a whole load of prius videos on youtube about the "pulse and glide" technique but far too much effort for me, and inconvenient for those behind you too.

You may also benefit from having the car in Eco mode when using cruise control, obviously a patient 60mph will see much better mpg.

ganzoom · January 17, 2017

'premium' petrol will make no difference to mpg in a IS300H. Mpg is mainly determined by how you drive and rain/wind/cold.

In summer i can get close to a reported 70mpg in the IS on a 100 mile M-way run. Currently in winter the best I can get is 50-55mpg. But I drive like a old man, I use to see 35mpg+ in my old 3l twinturbo BMW 335i and I can get over 100 miles on a charge from the Leaf which is 15 miles more than the offical EPA rating :).

olliesgrandad · January 21, 2017

Currently my 'Real World' figures per tankful are around 42-43mpg. A lot of my driving is motorway though and wth cruise control set at 71mph in eco mode. I tend to leave the car in eco mode as it is all too easy to find myself speeding if in normal or sport. The computer usually indicates a couple of mpg more. I have covered just over 6,000 miles since buying the car t the end of October and my phone app is giving an average of just under 43mpg overall which I am very happy with. I always drive with the aircon and heated seats on so could probably do better if I drove with them off.

B1001 · January 23, 2017

My IS250 is getting 35mpg on motorway trips with some traffic and 25mpg around town. Interesting to see if the hybrid adds signifantly more mpg, which it seems to do under the right circumstances.

Stuart Aspey · January 23, 2017

My average since purchase is showing 42.2 MPG. But the 2 fuel ups are showing 38.6 and 42.1, so not sure what the car is thinking 😂

ColinBarber · January 23, 2017

On 1/15/2017 at 7:21 AM, Stuart Aspey said:

Hi all. I picked up my 13 plate IS300H Premium on Jan 5th and am finding that getting above 42 MPG seems difficult on my commute and work travels. How is everyone else getting on?

What type of journeys? Wrong time of year to be getting good mpg from a hybrid. Use your seat heaters and turn off the heating system to allow the engine to cut out rather than keep running to heat the cabin for the first couple of miles.

What pressures do you have your tyres set to?

No need to pulse and glide but when cruising a steady 30 to 40 mph you need to learn to lift off until the EV light comes on and then be gentle on the throttle to maintain speed without letting the engine start again.

Check you wheels after a journey to make sure one or more isn't hot - to make sure you don't have a brake that isn't dragging.

rayaans · January 23, 2017

3 hours ago, Stuart Aspey said:

My average since purchase is showing 42.2 MPG. But the 2 fuel ups are showing 38.6 and 42.1, so not sure what the car is thinking 😂

Welcome to the world of real world MPG!

Sounds about normal. You want to be accelerating rather swiftly. Slow acceleration leads to more use of petrol. Ideally you also want to maintain momentum through turns, roundabouts and gain speed when going down hills to pull you back up the other side without putting your foot on the accelerator pedal. Easier said than done!

Low mileages are going to kill MPG as the car takes a while to warm up. Anything below 10 miles and you won't go above 40mpg.

Dealkent · March 4, 2017

On 24/01/2017 at 0:09 AM, rayaans said:

Welcome to the world of real world MPG!

Sounds about normal. You want to be accelerating rather swiftly. Slow acceleration leads to more use of petrol. Ideally you also want to maintain momentum through turns, roundabouts and gain speed when going down hills to pull you back up the other side without putting your foot on the accelerator pedal. Easier said than done!

Low mileages are going to kill MPG as the car takes a while to warm up. Anything below 10 miles and you won't go above 40mpg.

How does slow acceleration lead to more use of petrol ? Serious question .

when I first got my 64 IS 300 h , is was averaging 54 mpg . I am now currently in Spain , but only getting 47 mpg . The Battery warms up real quick here , so the EV kicks in after a 2 mins . I thought I would get better MPG . I'm not using premium petrol .

at first when in Uk I was doing lots of journeys on M 25 & M 20 , maybe that's why I was getting 54 MPG .

any tips would be appreciated

rayaans · March 4, 2017

19 minutes ago, Dealkent said:

How does slow acceleration lead to more use of petrol ? Serious question .

when I first got my 64 IS 300 h , is was averaging 54 mpg . I am now currently in Spain , but only getting 47 mpg . The battery warms up real quick here , so the EV kicks in after a 2 mins . I thought I would get better MPG . I'm not using premium petrol .

at first when in Uk I was doing lots of journeys on M 25 & M 20 , maybe that's why I was getting 54 MPG .

any tips would be appreciated

Slow acceleration = greater time taken to reach desired speed.

The most fuel is used when accelerating - therefore, accelerating for longer uses more fuel than accelerating briskly to desired speed and then maintaining it using pulse/glide

IS300Hdriver · March 4, 2017

I think it's worth comparing mpg when accelerating vs time taken. Thrashing it will see mpg of around 5 whereas calmly sees more like 15-20, plus hard acceleration can use up the hybrid Battery charge rather than charge it.

I'm still not sure what's best, also whether to use Eco over Normal in city driving. Hard to keep the engine warmed up when it keeps turning itself off. Did notice the heated seats preventing EV mode on cold mornings.

Get about 53mpg at 70, 63mpg at 60mph. London start stop traffic around 42.

Ataul · May 15, 2017

Stuart have you tried upping the tyre pressure. Also what tyres are you running. Saw your post by chance and I've been in the same position with my CT. Bugged Lexus Birmingham about it a few times they just scratched their heads. Did their resets on it and sent me on my way. No change of course.

Read some posts about tyre pressures and having the right tyres. Bearing in mind I had worn mismatched tyres I decided to just go for it no harm in trying, upped psi to 35 fronts 34 rear (from 33 32 psi) . Guess what instant change from 42 mpg to 50 mpg easy.

After that decided to change all 4 tyres after that went for GT radial sportactive 215 45r17 xl it had a B C rating (rain and rolling resistance) put it upto 40 fronts 39 backs as I found it was slightly softer tyre. Tried 35 front 34 back edges where wearing faster than centre and mpg was low so went higher as it was still in tyre manufacturers range. End result is I get mpgs in the 50s now no problems with even wear.

So give that a go, dont go too high first just test it and see and let us know

Stuart Aspey · May 16, 2017

Thank you guys for all of your replies. Yes, as the weather is warming up, my display is showing an increasing average. I'm currently at 43.3 according to the car, but only 40.8 according to Fuelly.com lol.

I decreased my pressure to 30psi to provide a bit of comfort on my 225/35/18's, maybe i need to raise it back up to 34psi . .

Yes, i try to drive smoothly and brake calmly and search for the EV where possible. The MPG is coming up, but I think the Premium is heavier than lower level cars due to the extra kit and features? So i am conscious of that too.

I'm on Nexen tyres all round and they appear to have even wear at the moment. I'm gonna try Haida HD927's when it's time to change. I had these on my IS200 SportCross and would be looking forward to see how they compare on the IS300H.

I have just passed my 60,000 mile service with flying colours, so i shall be picking up a bottle of Forte Advanced Gas Treatment for Petrol Engines to clean out any carbon deposits that may have built up. I am using Supermarket 95Octane. Is there any benefit from trying 97 or 99?

rayaans · May 16, 2017

57 minutes ago, Stuart Aspey said:

Thank you guys for all of your replies. Yes, as the weather is warming up, my display is showing an increasing average. I'm currently at 43.3 according to the car, but only 40.8 according to Fuelly.com lol.

I decreased my pressure to 30psi to provide a bit of comfort on my 225/35/18's, maybe i need to raise it back up to 34psi . .

Yes, i try to drive smoothly and brake calmly and search for the EV where possible. The MPG is coming up, but I think the Premium is heavier than lower level cars due to the extra kit and features? So i am conscious of that too.

I'm on Nexen tyres all round and they appear to have even wear at the moment. I'm gonna try Haida HD927's when it's time to change. I had these on my IS200 SportCross and would be looking forward to see how they compare on the IS300H.

I have just passed my 60,000 mile service with flying colours, so i shall be picking up a bottle of Forte Advanced Gas Treatment for Petrol Engines to clean out any carbon deposits that may have built up. I am using Supermarket 95Octane. Is there any benefit from trying 97 or 99?

30psi seems abnormally low.

The Premier should be on 36psi all around which will no doubt reduce fuel consumption slightly.

You're unlikely to see a benefit in using premium fuels and if there is a slight MPG benefit, it'll be negligible once the extra cost has been taken into account.

Ataul · May 16, 2017

My god must feel like a slug driving around with those pressures. I guess to get more comfort your going to have to sacrifice mpg and tyre wear.

Only other way is to go down to 17" rims with a wider tyre wall this will give you more comfort and better mpg.

I've tried 99 ron fuel but I guess its marginal probably not worth the extra you have to fork out for it, but try it yourself and tell us. I know it burns cleaner.

Blisteringblue · May 18, 2017

Not far off 100k in my 2014 SE now and my MPG has never changed. 48 in the winter and 52 in the summer. Bear in mind the SE has 16s though.

Will be upgrading to a Sport next month and I guess I will notice a real difference going to 18s so will have to get the levels right.

Low 40s just seems too low though.

MONTIMAR · May 19, 2017

I have just completed a proper fuely ( tank to tank ) for the first 1000 miles and it averaged 55 MPG. Most of my journeys are above 40 miles on A/B roads with just the odd shopping trip. Using the computer readings the worst has been 42 MPG on a 10 mile run and the best 74 MPG following a 75 mile run from Leyburn on a warm day and a warmed up engine. Short journeys from cold are a real killer and I have never been on a motorway.