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RX450H Engine changes circa 2017 - increased CO2 emissions


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I'm researching for a RX450H Premier and notice there was a change in the CO2 emissions around 2017 from 127g to 134g/km to  138g/km CO2. Does anyone know what changes were made to the engine which caused this change and also the reduction of quoted mpg. I'm aware that the mpg figures may have changed due to the use of the new WLTP measurements but I'm curious to know if the higher CO2 output has any material change on the performance or values compared to the previous versions. Many thanks

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The engine was updated for the RX4 late 2016/early 2017 which gave it a few extra ponies going from 297BHP to 305BHP or thereabouts.  The newer version is also slightly larger and as it uses the same hybrid train as the older one, one assumes that with slight engine tweaks and the larger size it may also have been a little heavier than the outgoing 2016 RX3 model which had a max kerb weight of 2200Kg in Premium trim.

It was 2017 that Lexus amended their fuel consumption figures, not that they were really much different to the outgoing model which claimed way optimistic fuel economy.  Lexus released figures which amended earlier 54mpg claims back to 44mpg which some, with a following wind on the flat, claimed they could just about achieve although real world for mixed driving remains low to mid 30's.

The higher CO2 would be a cost at a guess of the larger vehicle but with revised RX4 models claiming improvements over the outgoing RX3 in this area, not a lot of that makes sense.  There is little real world performance difference between RX3 and RX4 models.  Tests were conducted using the RX3 F-sport which was measured at 6.8 seconds 0-60mph and a standing 1/4 mile of 15.1 seconds.  Lexus claimed I think closer to 8.5 seconds.  The RX4 is claimed to be 7.7 seconds and was tested at about 7 seconds.

Take all of this with a pinch of salt as the output such tests are HIGHLY dependant upon the fuel used and the altitude at which these tests were conducted so they could vary by a second and a half either way depending on where in the world you are and on the octane rating of the fuel used.  Suffice to say for a large barge using a modest 247-250 BHP V6 with electric motor assistance, they are sprightly enough although due to the combined torque figures (note, these have never been released to my knowledge....quoted torque I think is for the gas engine only, although I may be mistaken on this) not in the same league as some of the competition as that is not what they are all about.  Refinement and comfort over longer journeys is their forte, not high performance.

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Hi Paul

 

Thank you so much for your detailed explanation. It is really appreciated !

I'd searched the forum and the internet without much success but looking at the various sites, including Lexus Used, the data on mpg and CO2 did vary quite a bit. I also found that a lot of adverts are wrong, with a number of cars being advertised as standard RX450H but the spec and technical information relates to the long wheel base version, where the data is very much different. There just doesn't seem to be much consistency.

I'm looking for a Premier and as such, budget permitting, I prefer to go for the most up to date cars. I can't quite stretch to the latest facelift versions with Android Auto etc, but I'm not that bothered about that given I prefer to concentrate on my driving, not what's going on in social media world. The mpg figures are always a fairy story, although my Jag XK was pretty close to what was advertised, depending on driving conditions, routes taken, driving style etc. I managed to get 26mpg on average but as low as 13 and as high as 33, depending on whether I was being spirited or careful, if you get my drift !  My NX gets 37 to 41 mpg on average but I'll be down to one car from now on.

Certainly the bhp and associated acceleration is plenty quick enough for me, in the UK anyway, i wasn't sure how big a change the engine tweaks were and the exact dates but the adverts show the change for post June 2018 registrations. There were some further tweaks on the latest facelifts too, but the emissions data remained unchanged.

Many thanks again for your input !! The search goes on......

 

 

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7 hours ago, Caldean said:

but I'm curious to know if the higher CO2 output has any material change on the performance or values compared to the previous versions.

There were no engine/drivetrain changes on the series IV RX between MY16 and MY17. In fact the only material change on the 2017 (built from Aug/Sept 2016) over the launch specification was an automated braking function added to the Rear Cross Traffic Alert and Intelligent Parking Sensors system.

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1 hour ago, ColinBarber said:

There were no engine/drivetrain changes on the series IV RX between MY16 and MY17. In fact the only material change on the 2017 (built from Aug/Sept 2016) over the launch specification was an automated braking function added to the Rear Cross Traffic Alert and Intelligent Parking Sensors system.

yes, it seems the change happen in the MY18 from what I can see

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1 hour ago, ColinBarber said:

There were no engine/drivetrain changes on the series IV RX between MY16 and MY17. In fact the only material change on the 2017 (built from Aug/Sept 2016) over the launch specification was an automated braking function added to the Rear Cross Traffic Alert and Intelligent Parking Sensors system.

That's true Colin but they did change the advertised specs from the 2016 3RX which was the point I was making above.

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2 hours ago, GSLV6 said:

That's true Colin but they did change the advertised specs from the 2016 3RX which was the point I was making above.

Agreed but I assumed Keith was referring to differences between years of the series IV, not between the series III and series IV as those differences are numerous.

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Yes, however the OP specifically called for comparisons of performance, power and emissions, hence that's all that I commented on and there was no mention in the OP of restricting responses to the 4RX.  The 3RX don't forget, was still being sold on forecourts new and unregistered, and the major changes to information supplied from Lexus were indeed between that of the outgoing 3X and the incoming 4RX. Have there been any significant changes to the IV engine and drive train Colin?  I didn't think there had been.  It's much the same now as it was in 2017...at least to drive (I was also satisfied that there was so little difference between my 3RX and the latest 4RX in performance after driving a newer one that I decided to wait until they came out with something lighter which will require more efficient motors and batteries).  Great car...just wish it was 500Kg lighter!  The niggles on handling, bushings wear and economy are much to do with it being overweight.  "Reassuringly heavy" some might say! 😆

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Thank you to you all for your input. I should perhaps have made my query slightly clearer. I've been looking at the Series IV RX450h models where I had seen the disparity in the CO2 figures, especially for mid 2018 models, although, given the unknown build dates, the changes may have started in 2017.

I'm currently in negotiations, as of this morning, with buying a RX450h Premier MY 2018 ( registered December 2018) in Sonic Titanium with 138g CO2, whereas if I'd gone for a June 2018 reg the CO2 was being shown as 127g. Not that the emissions concern me greatly as a private buyer, but I just wasn't sure what changes had been made to the engine to create the difference in the emissions figures.

One of the issues arising now is that there isn't a space saver spare wheel, whereas the official spec sheet from Lexus marketing at the time indicated it was standard on the Premier, rather than an option. I might be wrong so a bit of negotiation still required on this point. Otherwise, looks like being a good deal I'll be getting - fingers crossed.

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7 hours ago, Caldean said:

I'm currently in negotiations, as of this morning, with buying a RX450h Premier MY 2018 ( registered December 2018) in Sonic Titanium

I'm pleased to say I've now concluded the purchase so I'm now in the LOC RX450H club officially.  The space saver is there after all, once I'd told him exactly where to look. Pleased with the deal and spec - now just need to wait on it being delivered. 

Thanks again for all your help everyone

Keith

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On 2/2/2021 at 10:18 AM, GSLV6 said:

Have there been any significant changes to the IV engine and drive train Colin?  I didn't think there had been.  It's much the same now as it was in 2017

No, a tweak or two in 2018 for Euro 6d emissions and with the MY2020 facelift there have been changes to the engine, intake, exhaust, fuel tank etc. but nothing that is changing the power output so I doubt the driver could tell any difference.

 

The Euro 6 to 6c to 6d-temp and 6d have changed the way the testing/reporting of CO2 occurs which would account for some of the differences being seen. Also the CO2 varies between the grades and options due to weight and wheel differences.

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