Genuine MPG IS300h vs Displayed MPG.

[Gearoidmuar]

My last car was a Honda Accord Diesel which was very economical, but displayed 10% less consumption than you could demonstrate from full to full at the diesel pump.

My IS300h which I love is similar. I tested it full to full and it said 54.8mpg, actual mpg was 51.6. I'll do it again and I'll get it's the same.

Have any of you done this?

[michaelH]

Yes, that seems about right, in my experience. Similarly, speedos always seem to read high, and Lexus speedos are no different. So when I see someone claim that they get 50 mpg cruising the motorway at 75 mph, I wonder whether they are relying on the displays, in which case they are more likely getting 46 mpg at 70 mph. A rough but easy calculation of mpg  can be made from tank range. If you refill when the indicated range is about zero, the tank will probably need about 60 litres/13 gallons to brim fill. At 40 mpg that should mean you have covered about 520 miles on that tank; at 46 mpg, 600 miles, and so on.

[royoftherovers]

On Friday, July 29, 2016 at 4:41 PM, Gearoidmuar said:

My last car was a Honda Accord Diesel which was very economical, but displayed 10% less consumption than you could demonstrate from full to full at the diesel pump.

My IS300h which I love is similar. I tested it full to full and it said 54.8mpg, actual mpg was 51.6. I'll do it again and I'll get it's the same.

Have any of you done this?

My old E class estate has consistently shown an 8% error, with the OBC being  more optimistic then the brim to brim method.

My GS 450h is similarly overoptimistic.

 

Regards

John

[ColinBarber]

My IS is normally 2 to 3 mpg over, similar to any Toyota/Lexus i've had in the past. If you click on my Fuelly link, the notes against each fill-up have the readings from the fuel computer and fuelly has the real readings.

[Simpsoid]

I didn't think to record my fuel computer readings but Colin's figures seem to be pretty close to the ones I've been seeing: The computer does seem to overstate it by somewhere around 2.5 to 3.5 mpg.

Having been tracking my experience on fuelly.com also, what struck me most was the enormous difference between fuel economy at (a very respectable) 43.4mpg in coldest part of winter - although here in the milder southwest it wasn't that cold, of course and my best in the summer at 52.9 - almost 10 miles per gallon difference.  Wow!

 

[Gearoidmuar]

The exact same for me! I've stopped looking at the MPG which is pretty good and just love driving the car. The CVT which is much abused, is in my experience brilliant. It gives you ferocious acceleration where you need it. The car is so effortless to drive.