Poor MPG on a new is300h

[MONTIMAR]

I have just checked my records and my fuel cons varies from 50 mpg during cooler weather and 57.2 mpg during summer months. Most of my driving consists of long runs on A/B roads in eco mode so fewer cold starts and a light foot. I take the car off the road during the Winter as I move to warmer weather so my driving profile is as good as it gets.

[Danny Furey]

How come the trip says I have 3 miles range left, I refuel till brimmed, it takes 59litres when the tank capacity says 66 litres?

[route66]

On 1/20/2021 at 8:24 PM, Danny Furey said:

How come the trip says I have 3 miles range left, I refuel till brimmed, it takes 59litres when the tank capacity says 66 litres?

Because the trip computer is very conservative!

I've looked at this in detail and compared my reported remaining range with the real range (When refueling, I always fill it up, calculate what was left in the tank and see how far this would have brought me based on the calculated MPG for that tank). The results taken over 44 fills show an average surplus of 40+ miles with 2 refills showing a surplus in the 20s and 3 in the 70s.

And this is the additional distance you would have been able to travel after the trip says zero range - the red light will have been nagging you for some time before that. Once, I did a little over 20 miles after the range said zero. It took nerves of steel but when I filled it up, it took 60.75 litres - the 5.25 litres remaining would have been enough for an additional 64 miles !!!

And yes, I know you'd be daft to aim to refill when the tank is near empty - sediment and all that - nevertheless, I would much prefer an accurate guide so as to avoid both myself and the computer having a reserve.

[Slicendice1]

I have a Lexus is 300h, 2017.  I have had it about 2 years, and it has around 48,000 miles on the clock.  In summer when temps over 22-23 degrees usually gives 43-48 mpg (UK gallon) urban driving.   Motorway 55+
Winter (minus degrees to 10 ish) I get 32-35.  This has been pretty consistent until this month when my summer readings dropped to 35mpg about 10 less than it should be which is worrying (and temps are 30+ 25+ 22+ etc).

I usually drive in sports mode too.  I drive using good hybrid braking 😉 and don't race around too much s- my style has not changed recently so suspecting dirt build up in the fuel systems or air filter perhaps.

 

[Zotto]

Sport mode is not the best for fuel sparing, try using normal or ECO. Another suggestion with high temperatures is to use  AC to keep HV Battery pack in good temperature range, and a recommendation to verify good air ventilation trough it. You should hear hv Battery fan only with cabin  at high temperature; usually I set my AC to 24 Celsius degrees.

[wharfhouse]

3 hours ago, Slicendice1 said:

I have a Lexus is 300h, 2017.  I have had it about 2 years, and it has around 48,000 miles on the clock.  In summer when temps over 22-23 degrees usually gives 43-48 mpg (UK gallon) urban driving.   Motorway 55+
Winter (minus degrees to 10 ish) I get 32-35.  This has been pretty consistent until this month when my summer readings dropped to 35mpg about 10 less than it should be which is worrying (and temps are 30+ 25+ 22+ etc).

I usually drive in sports mode too.  I drive using good hybrid braking 😉 and don't race around too much s- my style has not changed recently so suspecting dirt build up in the fuel systems or air filter perhaps.

 

Best mpg is when outside temperature is about 20C - more and the air con reduces mpg, less and the need to heat the cabin reduces mpg. However, assuming you are using air con etc same as previously a possibility is that the hybrid fan filter has become clogged - there is a detailed thread on here about cleaning the hybrid fan filter. Although your year and mileage are low (I have no issues on a 2014 136k mile IS 300h) if you have had a lot of dust or dirt in the car from transporting things or pets for example it could be your problem. 

[wharfhouse]

18 minutes ago, Zotto said:

Sport mode is not the best for fuel sparing, try using normal or ECO. Another suggestion with high temperatures is to use  AC to keep HV battery pack in good temperature range, and a recommendation to verify good air ventilation trough it. You should hear hv battery fan only with cabin  at high temperature; usually I set my AC to 24 Celsius degrees.

Yes Eco does make a difference - probably a few mpg as it reduces air con and makes the throttle less sensitive and uses the Battery to support economy rather than power - takes a few miles of driving after switching for the computers to adjust to Eco mode. I tend to use this for general driving and move to Sport if I'm in the mood for quick driving and overtaking. 

[ikeja]

I always use "normal" mode with AC "on" all the time and achieve between 48 and 55 mpg depending upon season, on mainly A roads and dual carriageways.

[Zotto]

Another difference is given by short  traits, first minutes of use are most fuel consuming ones, mpg are better in long distance trips.

[agent_dess]

7 hours ago, Zotto said:

Another difference is given by short  traits, first minutes of use are most fuel consuming ones, mpg are better in long distance trips.

I second that on longer trips in F-sport I get 50mpg.. normal local daily I get 38mpg

[immotek]

300h, I drive with eco mode on at all times and air-con on auto. Mainly school/shopping runs and average around 43-44mpg.

[Robertdt]

300h F-Sport here and ive been getting 46 ish for last 6 months daily driving, Always in sport mode with Air con on. Ive never found that eco makes any noticeable difference and on long runs the best ive had is 49

Rob

[IS300FSPORT]

55 minutes ago, Robertdt said:

300h F-Sport here and ive been getting 46 ish for last 6 months daily driving, Always in sport mode with Air con on. Ive never found that eco makes any noticeable difference and on long runs the best ive had is 49

Rob

Eco does make a noticeable difference at least on mine, on local routes <40MPH It looks for any opportunity to switch to EV. In Sport its ready to go engine stays on longer probably for the extra kick, on local route Sport mode is unnecessary unless your looking to make a quick get away its v lively not ideal in slow moving traffic. Just my view on it, I stopped paying attention to the MPG figures a while back. 

[Robertdt]

Sorry i meant no notable difference to fuel economy. 

45 minutes ago, IS300FSPORT said:

Eco does make a noticeable difference at least on mine, on local routes <40MPH It looks for any opportunity to switch to EV. In Sport its ready to go engine stays on longer probably for the extra kick, on local route Sport mode is unnecessary unless your looking to make a quick get away its v lively not ideal in slow moving traffic. Just my view on it, I stopped paying attention to the MPG figures a while back. 

Just shows how different we all are, i gave up on eco 4 years ago as i find the sluggish pickup borderline dangerous. I also dont pay much attention to fuel economy.

Rob