IS300h - mpg question

[BigChange]

Car computer is usually around 10% optimistic.  My annual average for all roads,  conditions, seasons etc for each of the last 3 years is just over 47mpg.   Have to  assume that you need a very light foot indeed and French autoroutes to achieve the Lexus published numbers. 

[Jayw13702]

Yes, it’s fair to say that the computer does read optimistically.
However with hybrids there are also other factors that will affect your fuel consumption, tyre pressures being the most common, the state of the 12 V Battery being another and finally the operating temperature of the hybrid Battery and the state of the cooling fan for that.

Last year my fuel consumption started to drop off quite badly, it transpires that the vents by the back seat was being blocked off and so the Battery was running out of its optimal temperature range


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[Andrew888]

For me the winter time I'm averaging around 42mpg, in the summer I'm probably hitting 45mpg or so

[darrude]

Why do people say that hybrids are no good on motorways...

I only do long journeys in mine, always get over 50mpg, closer to 60 in summer if there is no traffic.  Is there a 220bhp petrol automatic non hybrid that is that efficient. Even diesels struggle to get close with that power output.

[matt8]

2 hours ago, Jayw13702 said:

the state of the 12 V battery

Hi Jay

I am interested in knowing how a 12v Battery in poor condition can affect the MPG.

Thanks!

[matt8]

Jan 2018 - Jan 2019.

Lots of short journeys, occasional long runs.

Averaged 38 MPG across 6000 miles (measured brim to brim every time, recording miles travelled and calculating). I've a 2013 F-Sport.

Doesn't seem that high. Have I got a problem with my car would you think?

[Jayw13702]

Hi Jay
I am interested in knowing how a 12v battery in poor condition can affect the MPG.
Thanks!

When the 12v starts to get old they draw more and more frequently from the hybrid Battery.

It’s a gradual thing, but eventually you get to a point where you notice it.

On the prius we used to get about 7 years out of a 12v Battery, given that the oldest 300h’s are 2013 it’s something we may start to see soon


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[wharfhouse]

1 hour ago, darrude said:

Why do people say that hybrids are no good on motorways...

I only do long journeys in mine, always get over 50mpg, closer to 60 in summer if there is no traffic.  Is there a 220bhp petrol automatic non hybrid that is that efficient. Even diesels struggle to get close with that power output.

It's an argument that keeps circulating - the premise is that if you can maintain a high constant speed for a lot of miles on an empty motorway then a) a diesel engine will be more economical (maybe 10mpg or so more?) and b) a petrol engine will not be too different since the hybrid is essentially running as a petrol engine at that point (although the Atkinson cycle on the hybrid is more efficient still than the Otto cycle of a normal ICE). But, when you factor in real life for most people which is that driving for very long at a high and regular speed in the UK, especially during normal working hours, is nigh on impossible and usually punctuated with i) weight of traffic causing slow or variable speed running or ii) roadworks and slow lane running usually at 50mph or iii) smart camera controlled motorways often with speed restrictions, then in all of those situations the hybrid unit is doing what it does best by harvesting energy when braking and deploying it when accelerating whilst maintaining the ICE running at peak efficiency where possible. So yes, in normal every day use the hybrid will deliver good fuel economy on long motorway runs because the journey is more usually varying conditions at lots of different speeds. I have a colleagues with diesel and petrol engined cars and myself with the hybrid IS 300h. We all do some long distance runs (a few hundred miles) whilst traveling together in each others cars (similar types of cars and performance) and the above is clearly seen when comparing the consumption on the trip computers - on balance across a mixed journey on the motorway (so not all high speed running) the diesel and the hybrid are much the same with the petrol in 3rd place and falling off the more stop start the journey becomes. In particularly busy periods the hybrid will often come out slightly ahead.

So, the statement "hybrids are no good for motorways" is clearly a simplistic stirring of the pot and should carry a footnote " *when the motorway has little traffic, no speed cameras or road works"...

[wharfhouse]

1 hour ago, matt8 said:

Jan 2018 - Jan 2019.

Lots of short journeys, occasional long runs.

Averaged 38 MPG across 6000 miles (measured brim to brim every time, recording miles travelled and calculating). I've a 2013 F-Sport.

Doesn't seem that high. Have I got a problem with my car would you think?

Sounds like it could be about right for true brim to brim - if I take my 48mpg overall lifetime average on the trip computer for a car on 17" wheels and then subtract say 10% for the computer over estimating (other report this but I have never checked) and maybe another 10% for the difference from 17" to F-Sport 18" wheels (not sure how accurate this is but is for illustration) it would then be 39 mpg. Factor in driving style etc. and your figures sound ok. I also use Eco mode quite a lot - I find it makes quite a big difference at low speeds as the EV cuts in sooner and my acceleration tends to be a bit more subdued, and also at the other end I use Eco on long motorway runs too as I usually set cruise control on when I have some clear road and let the car do it's own thing. I have found that in Normal I drop about 5% in consumption and in Sport about another 10%+ but as I tend to only put in Sport when I want to get a shift on somewhere that's no surprise...

[Jayw13702]

Why do people say that hybrids are no good on motorways...
I only do long journeys in mine, always get over 50mpg, closer to 60 in summer if there is no traffic.  Is there a 220bhp petrol automatic non hybrid that is that efficient. Even diesels struggle to get close with that power output.

I kept being told that be a friend who had a 520 bmw of the same age as my 300h.

So for a bit of fun, and to shut him up! We reset both computers and ran up the M5 for 50 miles, both keeping to the same speed and where possible both using cruise.

I was 57.8mpg, he was 59.2mpg, the difference was so insignificant that he now accepts that the 300h may be suitable for motorways and urban


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[Stuart Aspey]

4 hours ago, matt8 said:

Hi Jay

I am interested in knowing how a 12v battery in poor condition can affect the MPG.

Thanks!

Just had my 12V auxillary Battery changed. Will monitor to see if MPG improves.

[ColinBarber]

15 hours ago, Stuart Aspey said:

Just had my 12V auxillary battery changed. Will monitor to see if MPG improves.

Very unlikely. The 12v Battery would need to have almost completely failed for a new one to make a noticeable difference in mpg - it is the same on a non-hybrid too. The alternator puts extra load on the engine if it is constantly charging the Battery.

[Linas.P]

I think one more thing to note - Average speed on free flowing motorway in UK is 82MPH (according to ONS 2016). Hybrid will always be more fuel efficient if you cannot get past 70MPH, I quite specifically stated petrol only becomes ~ comparable @80MPH and more fuel efficient @90MPH. Argument is purely theoretical in UK as in theory anything over 70MPH is illegal, but in other more sensible countries with 140KPH limits or more that becomes quite relevant.

When I say motorway, for me that mean cruise set @80MPH indicated (which is ~73.5 GPS) literally for 100s of miles - I do sometimes cancel cruise, but try to never brake (hypermyling of sorts)... if you get into traffic or if you fighting for outside lane i.e. accelerating to 90, then braking to back to 50 when 4 axle freaking crane creeps into 4th lane... that is not motorway driving. That I call "British road madness"... and there you certainly better with hybrid.

Anyhow going back to my practical example from my life - if I would have had IS300h instead of IS250 for last 4 years I would have saved £400 for my mixed driving. At the same time I woudl have lost £4000 in depreciation (comparison apples to oranges as obviously this is between mk2 and mk3), however if I would have say BMW 320d, it would have saved me £2000 only because of motorway MPG (probably would have spent £1000 on DPF and another £800 of plastic timing chain gears, but that is the topic for another day).

Point I am trying to make - sort of for and against at the same time. In the city hybrid will save so much money compared with petrol that it is worth considering, if you do quite a bit of motorway then the saving will be negligible. Even considering rather outdated IS250 mk3... I would rather have it with nice smooth petrol v6, than save £400 and drive anaemic hybrid. I am not saying Petrol will be better on motorway or hybrid woudl be outright bad, but the cost saving will be negligible. 

[Stuart Aspey]

10 hours ago, ColinBarber said:

Very unlikely. The 12v battery would need to have almost completely failed for a new one to make a noticeable difference in mpg - it is the same on a non-hybrid too. The alternator puts extra load on the engine if it is constantly charging the battery.

That's a very good point. The difference will be minimal and much more likely to be down to a multiple number of factors and not solely the change of Battery.

[cruisermark]

On ‎2‎/‎13‎/‎2019 at 9:58 PM, The-Acre said:

You'll regret it!  I tried it with a GS last year.  I loved the GS at first, more modern looking, sportier to drive, more economical (I managed 43mpg on one long trip) but after three months I was longing to get back in an LS.  It ended up losing me money, then costing me more to buy an LS (albeit a Celsior) but there's nothing like it.  Maybe it'll be different for you Mark, but I learned the expensive way!  The LS is an itch and I've yet to find anything else to scratch it. I think only those who have had one would understand that.

Phil you are right and I know that after driving the LS for so many years - I even had problems adjusting from LS400 to 430 - that's how picky I am (or was) but I just want to try something different and bit modern. 

[cruisermark]

Thanks everybody for your replies - it makes interesting reading.

I'm not overly fussed as to what mpg it gives - It will be cheaper than the 430 to run in terms of fuel/road tax and insurance.

I have never driven a modern Lexus or a hybrid so that will be a new experience. I like the size and love the styling of the 300h. The cockpit design is one of the best unlike BMW 3 series where it just drops down rather than slope around.

I like the f sport front a bit more - is the ride very hard in them - we have a BMW 335D m sport in the family - how does the ride compare? I know it may not be on par with the LS - I just hope the ride is not too crashy

[ganzoom]

1 hour ago, cruisermark said:

Thanks everybody for your replies - it makes interesting reading.

I'm not overly fussed as to what mpg it gives - It will be cheaper than the 430 to run in terms of fuel/road tax and insurance.

I have never driven a modern Lexus or a hybrid so that will be a new experience. I like the size and love the styling of the 300h.

Not sure how old your 430 is but I think you find the IS300H is a big step change in overall tech. The hybrid drive train works very well in town, and at M-way speeds, its only when you smash the pedal you notice the deficiency in throttle response/torque, but that's not what most people care about.

Your 100% right about running costs, our IS is £10 a year VED - there is a few which are £0 I believe. In another post people are mentioning such high servicing costs, if your going to use a main dealer than expect main dealer prices, I'm using our local independent to service our IS and its no more than any other car. But unlike my old BMW (and friends Audi/Mercs etc), aside from an annual service nothing else ever seems to go wrong. 

As for mpg, my wife mainly uses ours, but I do all the fuel ups. Never seen below 40mpg even in worst traffic/cold, on long M-way runs 45-50mpg regardless of speed of travel. If you hypermille you can get close to 60mpg. Long and short to it, interms of fuel costs its cheaper to run than our old diesel Civic. 

Enjoy the new car :).

[wharfhouse]

9 hours ago, Linas.P said:

I think one more thing to note - Average speed on free flowing motorway in UK is 82MPH (according to ONS 2016). Hybrid will always be more fuel efficient if you cannot get past 70MPH, I quite specifically stated petrol only becomes ~ comparable @80MPH and more fuel efficient @90MPH. Argument is purely theoretical in UK as in theory anything over 70MPH is illegal, but in other more sensible countries with 140KPH limits or more that becomes quite relevant.

When I say motorway, for me that mean cruise set @80MPH indicated (which is ~73.5 GPS) literally for 100s of miles - I do sometimes cancel cruise, but try to never brake (hypermyling of sorts)... if you get into traffic or if you fighting for outside lane i.e. accelerating to 90, then braking to back to 50 when 4 axle freaking crane creeps into 4th lane... that is not motorway driving. That I call "British road madness"... and there you certainly better with hybrid.

Anyhow going back to my practical example from my life - if I would have had IS300h instead of IS250 for last 4 years I would have saved £400 for my mixed driving. At the same time I woudl have lost £4000 in depreciation (comparison apples to oranges as obviously this is between mk2 and mk3), however if I would have say BMW 320d, it would have saved me £2000 only because of motorway MPG (probably would have spent £1000 on DPF and another £800 of plastic timing chain gears, but that is the topic for another day).

Point I am trying to make - sort of for and against at the same time. In the city hybrid will save so much money compared with petrol that it is worth considering, if you do quite a bit of motorway then the saving will be negligible. Even considering rather outdated IS250 mk3... I would rather have it with nice smooth petrol v6, than save £400 and drive anaemic hybrid. I am not saying Petrol will be better on motorway or hybrid woudl be outright bad, but the cost saving will be negligible. 

We are in general agreement on the mpg/cost side of things regards motorway driving - although we might have to agree to disagree on some of the more subjective points but if we didn't all have different needs at different times of our lives then the world would be rather boring!

You were looking at getting a BMW as a company car at one time weren't you - did you decide to stay with your Lexus in the end then?

[Stuart Aspey]

Servicing costs are an issue if you take out extended warranty. I'm just finding out now, that unless I get my 6 year old IS300H Serviced at Lexus, my warranty becomes void. So I am currently looking at another service plan to spread the costs.

[Pink]

4 hours ago, cruisermark said:

Thanks everybody for your replies - it makes interesting reading.

I'm not overly fussed as to what mpg it gives - It will be cheaper than the 430 to run in terms of fuel/road tax and insurance.

I have never driven a modern Lexus or a hybrid so that will be a new experience. I like the size and love the styling of the 300h. The cockpit design is one of the best unlike BMW 3 series where it just drops down rather than slope around.

I like the f sport front a bit more - is the ride very hard in them - we have a BMW 335D m sport in the family - how does the ride compare? I know it may not be on par with the LS - I just hope the ride is not too crashy

I came from a 530d with 19” wheels on M Sport suspension to an IS300h exec on 17” wheels, so more compliant than the 18” on the F Sport you’re considering. 

Have to say that whilst it’s definitely more comfy than the M Sport, even on the 17s its still fairly firm - more so than I was expecting. Given there’s the F Sport option, I’m a tad disappointed that the Exec model isn’t more compliant as standard. So would be interested to see how you find the FSport

Compared to the LS I’m pretty sure you’ll also notice much more road / tyre noise. Again, slightly disappointing but actually a victim of the relative quietness of the hybrid drive. But the LS would’ve been equally quiet, if not more so due to better sound proofing, so you might find the IS tyre noise instrusive.

Apart from that, and despite what it may sound like, I’m actually loving the way the IS drives !!

[Linas.P]

3 hours ago, wharfhouse said:

We are in general agreement on the mpg/cost side of things regards motorway driving - although we might have to agree to disagree on some of the more subjective points but if we didn't all have different needs at different times of our lives then the world would be rather boring!

You were looking at getting a BMW as a company car at one time weren't you - did you decide to stay with your Lexus in the end then?

What is boring is that Lexus only gives option of 300h nowadays.

I haven't really consider BMW as company car, not sure what you are referring to - the only thing I might have said Lexus 300h option is not allowed with new company car salary sacrifice schemes (from 2017), only BMW530/330e (and similar plug-in hybrids). So I said Lexus missed the trick with compliance in UK.

[wharfhouse]

21 minutes ago, Linas.P said:

What is boring is that Lexus only gives option of 300h nowadays.

I haven't really consider BMW as company car, not sure what you are referring to - the only thing I might have said Lexus 300h option is not allowed with new company car salary sacrifice schemes (from 2017), only BMW530/330e (and similar plug-in hybrids). So I said Lexus missed the trick with compliance in UK.

Ah ok - that must have been it then and I thought you were considering a BMW... Although I use my IS 300h for business use I have the luxury of also owning the company so have a completely free choice of cars.

[cruisermark]

mmm interesting points gareth - we have a 520d m sport with 19s in the family and I find the seats and suspension too firm - I think I have to test drive one to see.

I must add the LS430 is so quite locally that I do ask myself whether you can get any quiter

[ColinBarber]

On 2/15/2019 at 9:07 AM, cruisermark said:

I like the f sport front a bit more - is the ride very hard in them - we have a BMW 335D m sport in the family - how does the ride compare? I know it may not be on par with the LS - I just hope the ride is not too crashy

I'd suggest you test drive a model with 17" wheels. Ones with 18" are a bit hard and the F Sport a bit more crashy with its different suspension.

[mikejt]

I chose the F Sport and one big consideration is ride quality and Mway road noise. It's a firm ride but soaks up the potholes really well. Steers smoothly and precise for epower steering. Mpg has worsened in cold weather but I'm not high miler, got 50mpg in sept. now around 39 in the fast lane. It's a real smooth operator, get one. Look for elec. leather seats,  ML etc etc. or just get the Premier w all the toys.