"Yet another MPG thread" - RX450h

[Coxy]

On 05/02/2017 at 2:14 PM, GSLV6 said:

Well, as mileage grows, my average is slowly climbing up.  Best cross-country has been close to 44mpg now (so official figures CAN be had if on the flat!) and overall average is 28.5.  We have a lot of hills here though and from cold, it's fuel-sapping no matter what you drive. Our 2 litre Merc diesel estate managed about 36mpg overall and 32 to 36 locally so not  lot better. 

I've noticed that keeping speeds between 65 and 70 om motorways gets best economy.  Over 70 makes a big difference!

 

All things being equal on average most cars are anywhere from 10% to 15 % less efficient at 80mph than they are at 70mph. That figure is just from trying to get through the air resistance alone and won't factor increased frictional loads like tyres and drivetrain working more RPMs thus increasing frictional loads further.

That all adds up after a while.

[Glover]

Switched back to eco mode a few weeks ago having seen my round town mpg drop 24-25.  Immediate improvement to 32 and last weekend a combination of city, cross country and 70mph dual carriageway saw 40.1.  My average since last May when I bought my 3RXh is 35.8; my best last summer was 45.1.  I'm now running on Cross Climates at 36PSI all round; previously standard factory fit Dunlops with the same pressures.  Re the EV option on the steering wheel menu; try as I might I can never get it to go into that mode even with a fully charged Battery.  I don't know what I need to do to get it to operate but any advice gratefully received.

[GSLV6]

On 27/02/2017 at 6:43 PM, Coxy said:

 

All things being equal on average most cars are anywhere from 10% to 15 % less efficient at 80mph than they are at 70mph. That figure is just from trying to get through the air resistance alone and won't factor increased frictional loads like tyres and drivetrain working more RPMs thus increasing frictional loads further.

That all adds up after a while.

Yes, that's true.  The laws of physics stand irrespective of who makes a car!

Disappointingly, my average since picking the car up has dropped to just 28mpg over 1100 miles.  That's not good.  I don't know how anyone is getting mid 30's average in one of these as I drive carefully.  Mind you, to get anywhere here, you have to climb a steep hill and from cold.  That, combined with a fair few shortish trips is what does the real damage. 

 

[Glover]

Hills are a killer and from cold will I suspect have a real impact. Luckily I either start off down hill or on the flat so by the time I reach a hill (and there are some beauties in Nottingham!) the car is warmed up and most of the time I have the bonus of a downhill stretch to partially compensate, which is probably why I find mid 30s very achievable. 

Did about 30 miles of mid to high 70s dual carriageway on Wednesday, which dropped my average by about .5/6 mpg (from 35.8 to 35.2/3) but recovered it to 36.2 once I started following tractors through Lincolnshire! My overall average over about 9,000 miles is 35.6, which should start to climb now the warmer weather is here.  I think terrain and temperature are the biggest factors; the slightest incline seems to put the dial into the power zone and the bar mpg indicator drops below 20. Move onto the flat and even at 70 it's in the mid 30s on the bar if you're on a flat, smooth dual carriageway.  The RX450 definitely doesn't like hills when it comes to fuel consumption.  And if its cold it's hard to get the right side of 30 except on a run

[DanD]

15 hours ago, GSLV6 said:

Disappointingly, my average since picking the car up has dropped to just 28mpg over 1100 miles.  That's not good.  I don't know how anyone is getting mid 30's average in one of these as I drive carefully.  Mind you, to get anywhere here, you have to climb a steep hill and from cold.  That, combined with a fair few shortish trips is what does the real damage. 

 

There are so many parameters to consider, and not all of them related to your driving style. Traffic conditions, speed, temperature, weather, aircon, topology... to name but a few. I normally average between 28-29MPG (as per previous posts), drving normally... by my standards anyway. I tried to use ECO mode for a couple of weeks and saw my consumption rise to 31-21MPG. However I find that ECO mode compromises my enjoyment of the car too much. It is acceptable around town, or for a leisurely coutry drive, but it seriously blunts performance. I don't think it is worth it for the sake of a couple of MPG. Also, one of the reasons I bought an RX was because of its understated performance.

On ‎07‎/‎03‎/‎2017 at 10:46 PM, Glover said:

Switched back to eco mode a few weeks ago having seen my round town mpg drop 24-25.  Immediate improvement to 32 and last weekend a combination of city, cross country and 70mph dual carriageway saw 40.1.  My average since last May when I bought my 3RXh is 35.8; my best last summer was 45.1.  I'm now running on Cross Climates at 36PSI all round; previously standard factory fit Dunlops with the same pressures.  Re the EV option on the steering wheel menu; try as I might I can never get it to go into that mode even with a fully charged battery.  I don't know what I need to do to get it to operate but any advice gratefully received.

What are your thoughts on the Cross Climate? - Or is it too early yet...?

[GSLV6]

 

18 hours ago, Glover said:

Hills are a killer and from cold will I suspect have a real impact. Luckily I either start off down hill or on the flat so by the time I reach a hill (and there are some beauties in Nottingham!) the car is warmed up and most of the time I have the bonus of a downhill stretch to partially compensate, which is probably why I find mid 30s very achievable. 

Did about 30 miles of mid to high 70s dual carriageway on Wednesday, which dropped my average by about .5/6 mpg (from 35.8 to 35.2/3) but recovered it to 36.2 once I started following tractors through Lincolnshire! My overall average over about 9,000 miles is 35.6, which should start to climb now the warmer weather is here.  I think terrain and temperature are the biggest factors; the slightest incline seems to put the dial into the power zone and the bar mpg indicator drops below 20. Move onto the flat and even at 70 it's in the mid 30s on the bar if you're on a flat, smooth dual carriageway.  The RX450 definitely doesn't like hills when it comes to fuel consumption.  And if its cold it's hard to get the right side of 30 except on a run

 

I never achieved mid 30's at 70mph. Even on long runs, the best has been 34mpg at a steady 70.  The tyres are OE Dunlops inflated to 36psi all round.  Eco mode I think is a waste of time and actually costs more mpg in hilly terrain as you're constantly having to put your boot to the floor if you don't want to creep about at 25mph on the hills.  I live in the Cotswolds, so hills are  a necessary symptom of the vistas!  

The terrain I think is the real killer for me.  Yet, my MK 3 GS300 did more mpg locally as well as much more on a run, with the best on a Lake District run last year of 44mpg on the motorway at a steady mid 70's.  I bought the RX partly as my mileage has increased and the fuel economy over the GS300 was just one draw.  The official figures are an impossibility of you live anywhere that isn't billiard table flat.  I do feel a little cheated by Lexus and whilst on a soap box, there are some totally unacceptable compromises on build quality (two meaningless words when spoken from the mouth of marketing men) too for the price of the car.  Bizarrely, despite all of this, it remains the only sane choice!

 

 

[Linas.P]

On 1/29/2017 at 0:25 PM, GSLV6 said:

So, rather disappointingly, on the hope of hybrid tech reducing fuel bills, it seems that it makes little to no difference for the RX over the Mk3 GS, mostly due to the extra weight and frontal area.

Hybrid tech makes improvements in start/stop traffic in the city. I have experienced and said that many times - it makes no sense if you living in rural area and doing mostly A/B roads or especially motorways.

The comparison with GS300 is as well not very fair, heavier AWD vs. lighter RWD obviously has no chances on motorway.

If you would compare say RX400 vs. RX450h doing 2x15miles per day in worst London traffic.. that would make something like 16 vs 28MPG - in other words decent improvement in efficiency. But on motorway, it is likely there would be no difference.

I have driven IS/RC300h on motorway and they returns worse MPG than IS250 @70MPH (about same @65), but where it really starts hurting is @90MPH - IS250 does like 34MPG, whereas 300h only 28MPG@90.

I keep seeing same thing for hybrids as previously for diesels. There is application for this configuration where it shines and that is urban start/stop... if you not doing urban start/stop everyday hybrid is not for you. Exactly opposite for diesels, they are extra urban cruisers - but "no no" for short journeys in the city.

Yet what we see people doing - getting hybrids in rural areas and getting diesels in the cities.... 

[Glover]

I don't find a problem with response in Eco but then again I moved from a 1.4 diesel to a 3.5 petrol with a couple of electric motors if you need a real shove! 

I quite understand about Eco and hills; I've noticed that too in fact until things kick in it feels like I'm back in the diesel! So although I've not done it before (although reading the earlier replies I should have when we went on holiday to North Yorkshire) I'll definitely revert to normal if I'm anywhere hilly but fortunately round here with the exception of part of the city it's either flat or rolling so Eco isn't an issue.

7 hours ago, DanD said:

There are so many parameters to consider, and not all of them related to your driving style. Traffic conditions, speed, temperature, weather, aircon, topology... to name but a few. I normally average between 28-29MPG (as per previous posts), drving normally... by my standards anyway. I tried to use ECO mode for a couple of weeks and saw my consumption rise to 31-21MPG. However I find that ECO mode compromises my enjoyment of the car too much. It is acceptable around town, or for a leisurely coutry drive, but it seriously blunts performance. I don't think it is worth it for the sake of a couple of MPG. Also, one of the reasons I bought an RX was because of its understated performance.

What are your thoughts on the Cross Climate? - Or is it too early yet...?

As for the Cross Climates I've done about a 1,000 on them and they are brilliant; excellent handling and really quiet

3 hours ago, GSLV6 said:

 

 

I never achieved mid 30's at 70mph. Even on long runs, the best has been 34mpg at a steady 70.  The tyres are OE Dunlops inflated to 36psi all round.  Eco mode I think is a waste of time and actually costs more mpg in hilly terrain as you're constantly having to put your boot to the floor if you don't want to creep about at 25mph on the hills.  I live in the Cotswolds, so hills are  a necessary symptom of the vistas!  

The terrain I think is the real killer for me.  Yet, my MK 3 GS300 did more mpg locally as well as much more on a run, with the best on a Lake District run last year of 44mpg on the motorway at a steady mid 70's.  I bought the RX partly as my mileage has increased and the fuel economy over the GS300 was just one draw.  The official figures are an impossibility of you live anywhere that isn't billiard table flat.  I do feel a little cheated by Lexus and whilst on a soap box, there are some totally unacceptable compromises on build quality (two meaningless words when spoken from the mouth of marketing men) too for the price of the car.  Bizarrely, despite all of this, it remains the only sane choice!

 

 

I've not noticed any compromises on build quality but perhaps I haven't been looking, what in particular have you found