Cledwyn

The MPG is never fabulous on 450h but it is terrible for the last week or so, can't even get over 30 when going down hill and no accelerator! (Would normally be 99.9). The rear engine appears not to be working when screen shown engine usage, and there is a weird muffled whomping sound from the rear. Any ideas? I have it booked in but not for another 10 days...

maseace

The rear only has an electric motor for all-wheel drive and acceleration. It will not be used most of the time during normal driving. The energy flow screen is not 100% accurate and just a general approximation of what's really going on. Not sure about the noise in the rear.

TommyTT

Have you done a ISC -idle speed control-reset Doing mine after I got it made mpg go from 19-20 up to high 20s.

I have copied the procedure from an earlier post. Here it is...
When you reset the ISC, you need to get the engine temp up to 181 degrees-normal. Then you idle around and drain the traction battery until the engine comes on, then shut the car down. You turn off all accessories and climate control (nothing electronic should be on). Put the car in run mode (start it), press the brake pedal, put the car in drive, then while holding the brake pedal down, press the accelerator pedal down.

The car will not move or rev much, but the engine will be on and start charging. Keep the gas pedal down for 40 seconds, then release it for a few moments, then down again for 40 seconds and keep doing that 40 on/10 off etc until the battery is fully charged (all green) and the engine no longer charges or revs slightly when you press the gas pedal down. Of course you're holding the brake pedal down all the time while doing this. Shut off the engine and place it in park. Wait 5 seconds.
Turn the ignition key back on to display "ready" -- make sure the A/C and heater system controls are set to off. Lightly step on the accelerator pedal with brake on until the engine starts -then immediately take your foot off the accelerator and let the engine run until it stops by itself. This completes the procedure.

Shut down, put your accessories back where you want them, then you can start up and go anytime. Learn about pulse driving to maximize your mileage going forward.