1020.6km on 42.04 litres


The hot weather has really helped improve my fuel consumption.  Despite using the A/C regularly to cope with the extraordinary heat, I was getting very good FC numbers.  At 482.8km my FC was 3.7l/100km (3.9 corrected) and the Distance to Empty (DTE) showed 442km. That’s a total of 925km according to the very conservative DTE reading.

If I’d maintained that 3.7 on the HSI (or 3.9 corrected) for the 925km, I would have used 36 litres from a 45 litre tank.

If I then drove using every last drop, those 9 litres would have taken me another 230km for a total of 1155km or 717 miles.

A 700 mile tank was within reach as long as a long line of ifs held true.  So then what happened?

  • Went in for 90,000km service.  After the 80,000km major service I got much better FC.  I’d hope for a reasonable gain this time, even though it was just a splash and dash;
  • But they used 10W-30 oil.  Call me fussy, pedantic and picky (never obsessive) but the thickest I’d expect is 5W-30.  I’d prefer 0W-20, anything but the treacle that was used;
  • By necessity, servicing uses petrol and drains the HV battery without adding much distance.  I had to use more petrol to build up the HV battery;
  • Tyres were rotated.  Do the Ovation ecovision at the front affect FC?
  • Another driver had the car for a few days.  She’s getting better, but she still accelerates too hard and brakes too late.  She’ll average 4.5-5.0l/100km, which is very impressive for a normal car, but not for my Prius.
  • Flat 12 volt battery.  The engine works harder to charge the 12 volt battery.  If it can’t hold a charge, the engine runs a lot more than it has to.
  • Engine Block Heater helped.  Even in Summer, Canberra mornings are cold.  Especially for short trips, pre-heating the engine saves petrol.

When I filled up today I had travelled 1020.6 km using 42.04 litres at 4.119 l/100km. (3.8l/100km on the HSI)

Is there another 125km in the tank?
Is there another 125km in the tank?

I think that I could get 1126km (700 miles) out of a tank, leaving a reasonable amount in reserve and a 5 litre Jerry can in the boot.  If the HSI reads 3.7 or better and I don’t fear using a few more litres (while not knowing where the bottom of the tank really is), I’ll have a real chance.

{For the record, I am not obsessive.  I know this because I’ve checked thousands of times.}

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