Going Long Distance in a Third Generation Prius

This year, I drove down to Melbourne to see the folks for Christmas and it was the first time making this trip in our new 2012 Prius (third generation). I’ve been working out how to improve the fuel economy from its initial achievements of around 5.2L/100km through various means such as adjusting tyre pressure but also allowing time for the vehicle to wear in.

Just to provide some context, the third generation Prius is rated for 3.9L/100km while our previous Prius (second generation model) had a rated fuel economy of 4.4L/100km. Theoretically, with a 45L tank in the third generation Prius you could travel in excess of 1000km on a full tank (1153km to be exact) which is well in excess of the 920km required to travel door to door from Sydney to Melbourne. However, I was somewhat irked on previous occasions in this new car that the cruising range seemed to top out at 820km and the last pip in the fuel gauge would flash just after about 800km. There are ten pips in the digital fuel gauge and you’d be forgiven in making the assumption that each pip represented 10% of petrol tank capacity but because of the shape of the tank this isn’t entirely accurate.

Anyway, as long as I could keep the fuel economy measurements under roughly 4.9L/100km for the tank of petrol then theoretically I could make the trip without having to fill up between Sydney and Melbourne. Anyway, I was able to manage 4.4L/100km on the Sydney to Melbourne leg but will see how Melbourne to Sydney goes and see if it ends up being any different.

That said, regularly living on the edge like a certain Seinfeld episode may not be a good idea. Apparently, running the tank dry (or close to) may end up exposing the fuel pump inside the tank. From what I gather, the fuel pump is designed to be cooled by the fuel in the tank so a lack of fuel can cause the pump to become warmer – repeated and prolonged overheating could potentially decrease its lifespan. Plus, you don’t necessary don’t want to pump every last drop out of the tank – there can be impurities that collect at the bottom of the tank and running that through the engine is definitely not ideal.

So while you shouldn’t make a regular habit of taking things to the limit in your Prius I think it’s also important to know its limits just in case you end up in a situation where petrol stations may be a little farther than expected.

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