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Gen3 RX450h combined MPG 44.9 - has anyone ever achieved 44.9 miles to a gallon?


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I owned a RX400h for 15 years and 186,000 miles and most of the time I could return around 32-34 miles to the gallon. Lexus quote 34.9mpg combined.

I changed to a Gen3 RX450h Premier 6 months ago, expecting better fuel economy, my journeys and driving style have not changed and yet I can't get above 30mpg (I know its winter and the engine is working more than summer, and I know the car weighs over 2 tonnes). Lexus official mpg is 44.9 but 30 is disappointing and a very long way short. 

Does anyone achieve anywhere near 44.9mpg or is this a case of inaccurate information or misrepresentation on the part of Lexus? 

 

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7 minutes ago, Ken Crawley said:

I owned a RX400h for 15 years and 186,000 miles and most of the time I could return around 32-34 miles to the gallon. Lexus quote 34.9mpg combined.

I changed to a Gen3 RX450h Premier 6 months ago, expecting better fuel economy, my journeys and driving style have not changed and yet I can't get above 30mpg (I know its winter and the engine is working more than summer, and I know the car weighs over 2 tonnes). Lexus official mpg is 44.9 but 30 is disappointing and a very long way short. 

Does anyone achieve anywhere near 44.9mpg or is this a case of inaccurate information or misrepresentation on the part of Lexus? 

 

I guess they have Ken.............................in their dreams.🤣

Lexus claims are produced in accordance with strict guidelines and to that extent are no more inaccurate or misrepresentative than the other manufacturers claims.

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Best I've ever had was a 50 mile round trip and managed 41.8mpg but never managed as high as that either before or since:

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1 hour ago, Ken Crawley said:

Does anyone achieve anywhere near 44.9mpg or is this a case of inaccurate information or misrepresentation on the part of Lexus? 

It was inaccurate EU economy standards that give a false reading, not misrepresentation from Lexus. The figure quoted was the lower grade model too, the Premier would be worse due to larger, heavier wheels.

The newer WLTP testing method seems much more accurate, especially for hybrids. The current RX has mpg of 35.3. Given the current generation is around 10% better than previous then it puts your model around 32 mpg which is probably about right - although you may not get there in winter.

 

When I had a 450h as a courtesy car when my 400h was in for a service I seemed to get around 3 mpg more on a similar journey.

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The official figures quoted for the 3rd RX Lexus and other cars at the time were not realistic for everyday road usage.  (Suggest you look at fuel consumption for vehicles of the time on Honest John site.)  A new official way of assessing fuel efficiency has since been introduced which is rather nearer reality. 

There are many factors that affect mpg, ambient temperature, tyre rolling resistance and pressure amount and direction of wind, how hilly journeys are,  how well 'run in' or worn out engine is, free flow of traffic or holdups, how close the car is held to it's optimum efficient speed and how hard acceleration avoided.  So with these possible variables fuel consumption will vary.

The best I ever achieved with my 3rd Gen RX450h was 37.8 with favourable conditions.  My average is about 31.5 but it is very hilly in Devon.   

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I average around 32mpg, 29ish in Winter and 34ish in Summer.  Best I achieved was 37.6 on an extended tour up to Scotland and back.  All my calculations are based upon full to full refills, although the onboard computer is very accurate too.

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20 hours ago, steveledzep said:

I average around 32mpg, 29ish in Winter and 34ish in Summer.  Best I achieved was 37.6 on an extended tour up to Scotland and back.  All my calculations are based upon full to full refills, although the onboard computer is very accurate too.

I achieve similar figures to Steve, although we live at the bottom of a hill, so all our short journeys, (mostly v v short for the last  13 months!) will always adversely affect the figures - so I'm quite happy to be achieving 31.3mpg ave

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I'm down to around 32 at the moment, again too many short journeys in cold weather. I've managed some journeys in summer cruising at around 50 on flattish country roads and through 30-40mph towns/villages where I've got around 40mpg.

It's not too hilly around these parts, but I still find a lot of occasions where I can lift my foot just enough to hold speed, that's what seems to make the biggest difference.

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Where I live, there's steep hills in all directions so from cold, doing the school run = 16mpg there (3 miles of uphill with one section at an average 12% for 1.5 miles), but I get 50mpg on the way back!  It's only a short trip so not really representative.  On average, each tank gets me between 27 and 29mpg.  On longer motorway runs it's more like 32 to 33mpg (indicated 75mph...I checked my speedo against GPS at an indicated 77pmh is a true 70mph).  Oddly, travelling at higher speeds (not excessively so) makes little to no difference.  The real economy is between 55 and 65mpg where I get 36mpg on the flat on a longer run if I'm really gentle with the gas pedal. 

By way of comparison, a friend's BMW X3 diesel (3 litre) manages 28 to 30mpg locally and up to 37mpg on a motorway run.  Not a lot in it and his only weighs about 1900 Kg so we can't expect more than high 20's on local run-abouts or low to mid 30's M-way.  Lexus figures are hopelessly optimistic, but so are those of all other manufacturers because they test them without wind resistance on a rolling road at a steady 56mph which is just not representative of true load and drag.

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2013 RX450h Luxury. Around town, right now with temperatures between -4 and 4 I get 28 MPG. Sunny drive to London and back (essential), 33MPG with heating on 1 bar, both seats heated on 1 and audio on, 60MPH on motorway. 70MPH and it drops down to 31-32MPG. I don't think I'll achieve 41MPG I did in my 2007 GS450h due to the size and weight of the vehicle. Overall really happy but nowhere near 44.9 which was probably achieved in hangar on rolls.

 

My work vehicle is 2021 VW Caddy with 2.0 TDI and DSG gearbox. This one returns 28 in town in current climate and 35MPG on motorway. Really interesting considering it's based on a Polo, has 2 seats, 2 doors and a steering wheel (I.e. not much in it). Caddy does 400Miles on full 55L tank. RX450h does 400Miles on full 60L tank of mixed driving. Caddy weights probably around 1500kg or even less and hauls some electrical equipment. 

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