I track my consumption vs. kilometres on a regular basis and noticed that I am now using about 5% more fuel per kilometre than earlier this year.

I was going to get my car serviced when I realised that the drop in efficiency corresponded closely with the abolition of the regular unleaded petrol. A small bit of reading revealed that the energy value of ethanol is much lower than that of regular petrol.

What irritates me is that the NSW government while trying to promote eco friendly fuel is still taxing the ethanol at a similar rate per litre as normal petrol. To be fair to the drivers, this tax should be based on calorific value so as to reflect how far the drivers can go per litre.

As it stands, the NSW profits from forcing the consumption of less energetic fuel when drivers use more to get the same distance.

Personally i changed to premium. I have found that i get better economy that way and it covers the extra cost of purchasing the premium.
Either way you are paying the same or maybe a little bit more, but what did we expect, this is government.

IMHO, anyone who chooses to use an ethanol blended fuel in their petrol designed engine, has more money then brains.
Of course you will use MORE fuel then running just on pure petrol as you've discovered, it's all about calorific content.
This idea of enthanol has only one objective, and that is to SUBSIDISE the sugar industry of NSW and QLD.
Utilising ethanol for fuel does not benefit the Environment in any way, in fact I strongly suspect the OPPOSITE is true in the manufacturing of the product.
IF, our Govt was really serious, regarding the environment, they'd legislate every Australian manufactured car come off the assembly line fitted to run on COMPRESSED NATURAL GAS, something of which we have in abundance and does not effect the evironment as does Dino fuel or manufactured fuels like ethanol.
Instead we practicly give the stuff away and allow International Corporations to make squillions of dollars out of it and when it's all gone, Australians will have nought.

Yes Shadow Minister, I understand that the lower price of E10 fuel is more than offset by the lower calorific value of ethanol compared to regular unleaded petrol. So it is more efficient to just use the more expensive old regular unleaded stuff or perhaps the premium stuff.

This being the case, of course our government should be taxing ethanol or ethanol blended fuels at a considerably lower rate.

Maybe itchyvet is right – we should be converting to LNG instead.

Whatever the case, we should be weaning ourselves off of our addiction to oil with great urgency, not so much for climate change reasons as for the reason that our society is precariously dependent on oil and prone to major upheaval if the price rises significantly, let alone if supplies become short.

A couple of comments on the discussion so far.
Ethanol is not taxed as petrol is. The Federal Government subsidises it's production with an excise rebate, 38c/litre before the Biudget, now 25c/litre.If Tony Windsor has his way this subsidy will revert to 38c/litre. Allowing for the lesser energy content of ethanol, 38c/litre means we, the taxpayers, at 38c/litre, are paying 57c/litre to replace one litre of petrol.
The other point is the feedstock for the ethanol. It is mainly grain. The Dalby grain ethanol plant uses 220000 tonnes of grain per year and Manildra at Nowra produces the ethanol mostly from grain and flour.
Grain is a poor feedstock, much less economic and environmentally friendly than sugar cane, with far greater impact on our domestic and global food supplies. The supply of grain feedstock from our variable harvests cannot be married to a fixed demand of mandated ethanol use.
Ethanol subsidisation must be based on differentiated feedstock, with grain ethanol not included.

I was under the impression that the calorific difference of ethanol is around 30% less, so in a 10% mix the theoretical difference would be about 3%. However the octane rating of the blend is higher, and ethanol being an "oxygenator" the difference in performance may not be at all apparent. If the car engine isn't worn that is, as good compression is needed to extract benefit from the higher octane rating.

As to feedstocks, while I agree mandated ethanol could skew grain prices and I too think ethanol should stand on it's own feet, farmers should not be prevented from getting the best return they can for their crops. Farmers are in the energy conversion business and should be rewarded accordingly.

Not forgeting distillers grains, where half(from memory) of the feed value still exists at the end of the process.