2020 RX 450H Fuel consumption

[Sybaris]

I am about to decided to go with or not go with a 2020 RX 450H.

What is the fuel consumption like on it?  Realistically in the UK most of my driving is local/town driving, maybe 3 times a year I drive from London to Southampton (and back), the occasional long motorway run and some short motorway runs, say 2 or 3 junctions combined with town driving.

My NX 200t does 34 MPG tops on motorways and about 23 MPG town.  Summer or winter.

I really would like to know if though its bigger, will the RX be more economical or will there be a big difference?  I hear hybrids work harder in the winter so this may be something to factor in if the difference is that big.

 

[Spock66]

The RX should be an improvement.

Honest John lists the real world fuel consumption at 33.8mpg, I am currently averaging around 35mpg over a few thousand miles.

Last weekend I did a 500 mile round trip to Cardiff and back, mainly motorways, 38mpg outwards, 42mpg coming back, cruise control set to the legal limit so mainly 70mph. Outwards was a pretty clear run, return journey quite a few hold ups (eg white van with no wheel on the M25).

Yes consumption is a little lower in winter, especially short journeys as the engine runs for longer to heat the car.

[mikey2001]

I'm getting an average of 37 mpg at the moment while the weather is warm. I usually get about 32 mpg in the winter. I've had upto 38-41mpg on longer journeys up to Fife this year, and Sutherland and Caithness last year. Overall average is about 35 mpg on all roads over 10500-odd miles.

[Sybaris]

Those figures are way better than I expected.  I was thinking that a 3.5 v6 would be very thirsty but that doesn't seem to be the case.

[b4u2]

@Sybarisoff you go to buy it 🙂

[Herbie]

1 hour ago, Sybaris said:

Those figures are way better than I expected.  I was thinking that a 3.5 v6 would be very thirsty but that doesn't seem to be the case.

It is and it isn't.

The V6 is just as thirsty as any other V6, it's being a hybrid that gives the extra mpg.

[Sybaris]

OK but if its giving me better MPG, doesn't that mean its not as thirsty as I am getting further and filling up less than with what I already have?

[Herbie]

8 minutes ago, Sybaris said:

OK but if its giving me better MPG, doesn't that mean its not as thirsty as I am getting further and filling up less than with what I already have?

No, not at all.

The hybrids have electric motors to supplement the petrol engine. When you're climbing a hill for instance, the engine may return, say, 10mpg normally. However, because it's getting electric assistance from the motors it doesn't have to work as hard so it may return the equivalent of, say, 16mpg (completely made up figures).

Also, there are times when the petrol engine will be shut off completely, such as being stood at traffic lights or when the car is on Battery power only, so you're saving mpg there too.

[Spock66]

58 minutes ago, Herbie said:

However, because it's getting electric assistance from the motors it doesn't have to work as hard so it may return the equivalent of, say, 16mpg (completely made up figures).

But all of the electrical energy in a self-charging hybrid is free, either recovered from regenerative braking or charged via the engine so the mpg figure is a true reflection of actual cost, unlike a PHEV where they quote a very high mpg but do not factor in the additional cost of electricity.

[Sybaris]

Ok I must be missing something and I am still confused.  I think what I am trying to ask is, mile for mile, will I be spending more or less on fuel with the 450H than I am with my NX?  If I put in £30 of fuel for example, say I get 23 MPG and have to fill up weekly to replace that £30 of fuel.  If I change up to the 450H, will that same £30 of fuel last me longer and for example I could go further and fill up less frequently?  Or does it being a bigger engine drink that £30 fuel quicker and would mean I need to fill up more often.   

[Spock66]

27 minutes ago, Sybaris said:

Ok I must be missing something and I am still confused.  I think what I am trying to ask is, mile for mile, will I be spending more or less on fuel with the 450H than I am with my NX?

As per the real world examples above the RX should be more fuel efficient, you put fuel in the car and that is your only cost.

[Illogan]

10 hours ago, Sybaris said:

I am about to decided to go with or not go with a 2020 RX 450H.

What is the fuel consumption like on it?  Realistically in the UK most of my driving is local/town driving, maybe 3 times a year I drive from London to Southampton (and back), the occasional long motorway run and some short motorway runs, say 2 or 3 junctions combined with town driving.

My NX 200t does 34 MPG tops on motorways and about 23 MPG town.  Summer or winter.

I really would like to know if though its bigger, will the RX be more economical or will there be a big difference?  I hear hybrids work harder in the winter so this may be something to factor in if the difference is that big.

 

My mpg figures (running on E10 fuel..

Today - 210 miles on A1, steady 70mph - returned 34.3 mpg

Last week 120 miles, all in town, up/down hill, loads of traffic lights/slow traffic etc returned 32.5mph

 

 

[Sybaris]

Thats pretty good compared to what I am getting at the moment.

[Haylands]

14 hours ago, Sybaris said:

Those figures are way better than I expected.  I was thinking that a 3.5 v6 would be very thirsty but that doesn't seem to be the case.

The RX has an Atkinson 4 stroke engine, "normal" engines are Otto cycle engines, the Atkinson is far more efficient but produces less torque than an Otto engine, this is where the motor generators come in, they fill in the discrepancy in torque as they produce maximum torque from standstill. It is the clever electronics that ensures everything runs together well and gives the RX it's better MPG... 

[Sybaris]

Hmmm, just been out for an hour in my NX and got amazingly 25 MPG in local traffic doing the school run.  I think it knows it could be replaced and is putting up a fight.  The bigger issue is will the trade up be justified?  

[RXtoNX]

My average mph over 33k miles of mixed driving is 35.7mpg. Around 37mpg during the summer and 33-34 winter time with an absolute best of 43.5mpg (all as per Fuelly logs)

As mentioned above plenty have shared their data. Unfortunately only you can make the decision.

[Spock66]

Lexus article on the Atkinson cycle for those who may be interested.

https://mag.lexus.co.uk/atkinson-cycle-engine-work/

[stringbender]

Thanks to Haylands for that info. and Spock66 for the link. Been driving all this time and had no clue about valve timings until now.

My current mpg reading is 37 mpg ( from lots of miles). When I had the 2005 I logged each litre and the display reading was rubbish. Overstated by about 2 mpg ! The 4RX is so much nearer to the truth that I've now stopped the fuel checks. 

It is remarkable that such a car can give so many miles to the gallon. On the motorway run over the weekend the figure crept up and up to that 37. And I wasn't dawdling at 56 mph either.

[Sybaris]

37 is very impressive, I  get 33 to 34 on a 100 mile open motorway at 70 mph.

I have never got anywhere close to 37 on the NX 200t.  So the RX looks like it is much better on fuel costs.  Hopefully the trip around the corner to Sainsburys can be done on EV power and sitting in all the temporary traffic lights and the rush hour crawl will be electric too.  So will save there.

What happens if I am stuck in traffic, its hot, the ac is on and my Battery drains, does it just switch to the engine?

[Spock66]

48 minutes ago, Sybaris said:

What happens if I am stuck in traffic, its hot, the ac is on and my battery drains, does it just switch to the engine?

Yes, exactly as you describe although it will be driving rather than the a/c that will drain the Battery, engine will run for about 5-mins or so to create some charge and then stop and repeat as required.

[Haylands]

The aircon is powered by an electric motor, so is the power steering, so it stays cool all the time, even with the engine off... The "EV" range is very limited, 1/2 a mile if you are lucky... it is very sophisticated so just let it do it's thing..!!

[RXtoNX]

38 minutes ago, Haylands said:

The "EV" range is very limited, 1/2 a mile if you are lucky... it is very sophisticated so just let it do it's thing..!!

Depends on speed I guess but I regularly manage 2 miles in 30mph zones 

[Spock66]

29 minutes ago, RXtoNX said:

I regularly manage 2 miles in 30mph zones 

Yes I get about the same from a full charge.

[mikey2001]

The RX will also manage up to about 45mph on the traction Battery alone, provided it has sufficient charge.

[John Booth]

Car 5 days old and on a 50 mile cross country trip averaged 39.6 mpg