RX450H+ EV range and ICE consumption

[Xez]

11 hours ago, Alan Thompson said:

Sits back and waits for those cleverer than me to blow my theory/calculation/premise out of the water.

Hi Alan, firstly I’m sure I’m not clever at all! However I’m intrigued to know roughly what electricity tariff you are on; is it one of the cheaper overnight ones?

I’ve tried a little exploratory maths on your data by reversing the amounts spent on petrol and electricity and assuming some underlying range rates - let me know what you think and where I may well be wrong.

So, if the £65 was spent on electricity at a tariff of say 25p/kWh that would mean 260kWh which if my experience of getting 2.7 miles/kWh is near accurate would cover a total of 702 miles.

Then changing £255.82 to petrol at £1.669 per litre would give 33.7 gallons, which at say 40mpg (maybe normal hybrid) would cover 1,348 miles.

Grand total would then be only 2,050 miles

if I change the electricity tariff from 25p to 7.5p the total mileage would increase to 3,688. So I think that there’s still some refinement needed to our calculations 😉

Cheers, Kevin 

[Alan Thompson]

1 hour ago, Pally said:

That really helpful. Many thanks Alan and makes perfect sense to me. I’m finding it harder to track how much charge the car has taken as I’m having to charge from a 3-pin socket still (curse of a looped supply and lack of response / urgency from SSEN) but guess I can estimate that closely enough with the miles per kw/h and total EV distance and calculating that from my total EV site de driven? 
 

I’ve been disappointed with the app and lack of details it provides. Similarly the bar graphs in the infotainment aren’t particularly informative; so checking the maths with you all is helpful.

I am using a 'dumb' charger (pre-smart ones that tell you more info), so I calculate my charges by using the lexus Link app to tell me the amount of charge remaining in the Battery - remembering that 30% is ringfenced and not generally used for driving. I then calculate how many Kw/h it will take to fill and multiply that by the cost of electricity.

I'm not on any fancy tariff so if there is 47% charge left in the Battery the formula I use is 18.1*0.53*0.2736 this gives a £ value of £2.62. 

I disregard the fact that there will be some 'leakage' which means I'm underestimating slightly, but it is near enough for me.

And yes I have a spreadheet 😁

[Alan Thompson]

6 minutes ago, Xez said:

Hi Alan, firstly I’m sure I’m not clever at all! However I’m intrigued to know roughly what electricity tariff you are on; is it one of the cheaper overnight ones?

I’ve tried a little exploratory maths on your data by reversing the amounts spent on petrol and electricity and assuming some underlying range rates - let me know what you think and where I may well be wrong. I can see your logic, but I don't know why you would swap the costs?

So, if the £65 was spent on electricity at a tariff of say 25p/kWh that would mean 260kWh which if my experience of getting 2.7 miles/kWh is near accurate would cover a total of 702 miles. By August last year I was achieving 3.2 kw/h - it had steadily improved from March, Range Guesstimate with a/c was mid 50's actual was mid 40's.

Then changing £255.82 to petrol at £1.669 per litre would give 33.7 gallons, which at say 40mpg (maybe normal hybrid) would cover 1,348 miles.

Grand total would then be only 2,050 miles

if I change the electricity tariff from 25p to 7.5p the total mileage would increase to 3,688. So I think that there’s still some refinement needed to our calculations 😉

I'm also talking NX not RX which will be heavier?

Cheers, Kevin 

Hi Kevin

Back in August 2022 when I wrote the original post I was on 27.35p, I have never been on a cheap electricity tariff, I don't have a smart meter. This can cause a problem with accuracy as I have to estimate the actual electricity taken. Increasing my electricity cost by 10% would reduce mpg to 85.

My figures look high because between 1/3/22 (when I collected the car and filled with petrol) and 17/8/22 when I next refilled, I'd done a lot of short trips meaning that I rarely used fuel, so the majority of my 3809 were completed on electricity. Unfortunately, I don't record the actual miles covered on electricity for each journey and I can't interrogate the car as I've swapped it for a new one.

I have looked back and can see that the last time I filled the car with petrol was 31/12/23 with 15256 miles completed since 1/3/22. (I changed it on 16/3/24and didn't fill up again so I've ignored anything after this date). 

Running my logic again for approx. 'whole of life' I'd got to:

All fuel cost Petrol 603.96 + Elec 1090.61 = £1694.57 

Approx. Average Cost per gallon 1.55*4.54609 = £7.05

1694.57/7.05 = 240.36 gallons

15256/240.36 = 63.47 mpg

or 59.5 mpg if I increase Elec costs by approx 10%.

Obviously, this will vary per car as we all live different lives, The vast majority of my trips are local, less than 20 miles, so covered on electric - sometimes I do choose to run on petrol so it's not sat around in the tank for ever. If you are running the ICE more often, the mpg will be lower?

@Ken R is this how you calculate your figures?

[Xez]

Hi Alan, it’s great to meet a fellow spreadsheet guru 😀 and thanks for sharing your insights.

I think that you and I are aiming to calculate different outcomes. My approach is to try to calculate/estimate the car’s underlying hybrid mpg once the pure EV range has burnt off.

My data since ownership last July now shows a total of 6,200 miles, 364.62 litres (80.2 gallons) and 1,140kWh of electricity. The car is showing a trip of 2.7 miles/kWh thus I have, in theory, covered 3.078 miles from my purchased electricity (2.7 x 1,140). This leaves 3,122 miles (6,200-3,078) covered by 80.2 gallons; giving a hybrid economy of 38.93 mpg

As my old maths teacher used to say QED (quite enough data, thank you)…😂

[Ken R]

4 hours ago, Alan Thompson said:

Hi Kevin

Back in August 2022 when I wrote the original post I was on 27.35p, I have never been on a cheap electricity tariff, I don't have a smart meter. This can cause a problem with accuracy as I have to estimate the actual electricity taken. Increasing my electricity cost by 10% would reduce mpg to 85.

My figures look high because between 1/3/22 (when I collected the car and filled with petrol) and 17/8/22 when I next refilled, I'd done a lot of short trips meaning that I rarely used fuel, so the majority of my 3809 were completed on electricity. Unfortunately, I don't record the actual miles covered on electricity for each journey and I can't interrogate the car as I've swapped it for a new one.

I have looked back and can see that the last time I filled the car with petrol was 31/12/23 with 15256 miles completed since 1/3/22. (I changed it on 16/3/24and didn't fill up again so I've ignored anything after this date). 

Running my logic again for approx. 'whole of life' I'd got to:

All fuel cost Petrol 603.96 + Elec 1090.61 = £1694.57 

Approx. Average Cost per gallon 1.55*4.54609 = £7.05

1694.57/7.05 = 240.36 gallons

15256/240.36 = 63.47 mpg

or 59.5 mpg if I increase Elec costs by approx 10%.

Obviously, this will vary per car as we all live different lives, The vast majority of my trips are local, less than 20 miles, so covered on electric - sometimes I do choose to run on petrol so it's not sat around in the tank for ever. If you are running the ICE more often, the mpg will be lower?

@Ken R is this how you calculate your figures?

Basically yes. I have a smart meter and so the electricity consumption should be accurate.

[Pm4]

18 hours ago, Alan Thompson said:

Hi Pally

I'm here snooping from the NX Forum - I've got to keep my eye on Ken R !! 😂

Anyway, I've copied and pasted a post from an NX 450h+ Range forum back in 2022 about how I calculate mpg - I do it over a longer time than a single trip though. Hopefully this might help?:

"I filled up on day one (1st March) with odometer showing 29 miles. I've filled up today with odometer showing 3838, not put any fuel in between. Today put in 39 litres (8.58 gallons) to fill again. That works out at 444 miles per gallon.

I am not naive enough to think that this is a true representation, so I thought if I add the cost of the fuel (£65) to the cost of all my electric charges (£255.82), divide that by todays fuel price per litre (£1.669) after converting to gallons, this will provide an equivalent number of gallons to the total cost, then divide miles covered (3809) by the equivalent gallons: 

All fuel cost 65 + 255.82 = £320.82 

Cost per gallon 166.9*4.54609 = £7.587

320.82/7.587 = 42.29 gallons

3809/42.29 = 90.06 mpg

Sits back and waits for those cleverer than me to blow my theory/calculation/premise out of the water.

What have I missed?"

Thanks for the info, does it match the mpg on the dashboard? 

[Pm4]

17 hours ago, Ken R said:

Welcome to snooping on the RX forum Alan! 😁👍 I trust all good with you and your new NX. Your calculation is spot on as far as I am concerned and exactly how I calculate the overall mpg. Your 90mpg is certainly impressive particularly with only your second refuel in almost 4000 miles!      (Your piling the miles on!) My overall when I had my NX was 72mpg.

First calculation (after 665 miles) on my RX coming in at 62mpg using the same formula although increased temperatures of late are translating to an improving EV range.

 

Yes, I have been checking on you too, to check if any more comments on your new RX vs NX.

Meanwhile I have tested an RX and while very quiet and comfortable and a bit more difficult to get out of the car once inside my garage, I found a small niggle for me....that may sound unimportant but makes a difference for me. When on motorways or straight roads I like to rest my elbows while still holding the bottom of the steering wheel, but I can't do that with my right elbow on the RX because is wider!

How weird am I? 🤣

[Alan Thompson]

3 hours ago, Pm4 said:

Thanks for the info, does it match the mpg on the dashboard? 

I never look at the quoted mpg.

[AWC]

On 5/6/2024 at 7:50 AM, Tom, said:

Alex - thanks for that. The £1,000 odd cost of an Ohme charger would take a long time to recover at a saving of 1.5p per Kwh! I think I'll stick with the good old 13 amp socket.

One issue I do have is that the Lexus charging programme cannot be set for both start and stop times, which is needed to make full use of the low cost period. I have overcome this by fitting an external 60 amp timer to the 13 amp supply, which I needed to do anyway because I have a heated pool. The pool does not have its own timer and I needed to heat it during the low cost period as well as charge the car.

Tom

I found the 4 hours of cheap electricity wasn't enough to fully charge the Battery overnight using the 13A charger which was a pain. If you factor in the lower cost power overnight for domestic use as well like running the dishwasher etc. the cost of a charger doesn't seem so onerous.

I do find it strange that the Lexus doesn't provide both a start and stop time for charging.

[Tom,]

Alex,

4 hours of cheap elecricity charges my car to about 80%. I don't do long journeys every day any more, so that suits me fine as 2 nights of charging takes me up to 100% even with daily trips to the local shops.

Interestingly, I did a longer journey today and now the weather has warmed up I achieved 48.2 miles on EV alone, up from 39 or 40 miles in the cooler weather.

[MrBee]

Hi

I'm new to the party - current looking into getting a 450h+ 

I saw a comment from someone on a Lexus RX group on Facebook that suggested the F Sport has a better Battery range! I think this is rubbish, but thought I'd bet check with the experts on here 🙂

Thanks 

[Xez]

Hi MrBee,

The F Sport is the RX500 that is a ‘traditional’ Lexus hybrid, albeit with a turbocharged engine and gears, not a PHEV with e-CVT as far as I’m aware. So your scepticism of the Facebook post is well placed. It’s only the RX450h+ that is PHEV and will provide the longest Battery range.

[MrBee]

1 hour ago, Xez said:

Hi MrBee,

The F Sport is the RX500 that is a ‘traditional’ Lexus hybrid, albeit with a turbocharged engine and gears, not a PHEV with e-CVT as far as I’m aware. So your scepticism of the Facebook post is well placed. It’s only the RX450h+ that is PHEV and will provide the longest battery range.

Hi Xez, the 450h+ is available in F Sport trim. 

Here is the person's post:

 

 

[Xez]

Hi, yes I’m sorry I’d missed that this version had been released (it wasn’t available last year when I got mine). However a couple of points: comparing the F Sport to the Takumi on the Lexus website and the performance is identical. Also I’m see an EV only range of 49.7 currently on my car. 
Kind regards 

[MrBee]

Yes, I thought it was identical. I have asked them on face2where the info came from. Surprisingly I have not had a reply 🤣

I'm impressed with your 49.7 mile range. What sort of driving is that? 

[Xez]

43 minutes ago, MrBee said:

What sort of driving is that?

It’s a combination of many very short stop/start journeys around the local area plus some 30-40 mile jaunts. Since purchase last July the car is averaging 2.7 miles per kWh.

[MrBee]

6 minutes ago, Xez said:

It’s a combination of many very short stop/start journeys around the local area plus some 30-40 mile jaunts. Since purchase last July the car is averaging 2.7 miles per kWh.

Ah yes, the crucial miles per kwh values 👍Very useful information.

I have a test drive booked in a couple of weeks 

[Ken R]

1 hour ago, MrBee said:

Ah yes, the crucial miles per kwh values 👍Very useful information.

I have a test drive booked in a couple of weeks 

Enjoy the test drive. Its a fantastic car! I've had mine since March and really enjoying the comfort and quality. I previously owned a NX450h and a NX300h prior to that and whilst there's not a great difference in overall dimensions the RX feels so much bigger and simply wafts along in true Lexus fashion.

[Xez]

Charged my car today and the EV range is showing 50.1 miles and 47.6 with A/C. I think that’s a new high…😀

[Pally]

That’s impressive. Does it gradually change the estimate based your previous trips or is it just from warmer weather?  Mine has gradually crept up to a high of 41.5 but nowhere near that level. 

[Xez]

As I understand the warmer weather will improve the performance, that in turn improves the recorded miles/kWh average that then increases the expected range. I don’t know if there’s any improvement due to the software update, but it’s possible.

[Ken R]

2 hours ago, Pally said:

That’s impressive. Does it gradually change the estimate based your previous trips or is it just from warmer weather?  Mine has gradually crept up to a high of 41.5 but nowhere near that level. 

I'm currently showing 44.9/43.6 (with aircon) and its gradually creeping upwards. Actual is also being achieved at these levels.

[Tom,]

Turn the A/C off and your EV range will leap up. Mine now shows 50 miles at every full charge.

[Pally]

About to do another long trip so put fuel in for the first time. Exactly 30 litres after a very slight fill after initial cut out to round it off.

641 miles to date. App says 414.5 miles on EV but unfortunately I don’t know how much of that is pure EV and how much is from normal hybrid mode once EV Battery dropped to 30%
 

So I make it 97mpg in petrol terms ignoring cost of electricitY with pure ICE economy just over 34 mpg

If I convert cost of electric at 19.5p kw/h (still on an old fixed tariff so can’t change yet) at the current indicated rate of 3m kw/h I make it 65mpg equivalent overall

That doesn’t account for some of the miles being electric from normal hybrid generated EV power rather than plug in. So the actual converted mpg should be a little better.

I don’t have the Podpoint installed yet due to a loop supply issue so I can’t keep an accurate record of how many kw I’ve charged from the mains.

 

[MrBee]

That sounds really impressive. 

I think I read somewhere that Audi (I think?) have a system in their phev that analyses your proposed route and works out the most efficient way to deploy the Battery. I don't suppose the RX has this? 

Or maybe it's more clever than that and is effectively doing this continuously?