chrisc, Yes.
Prices Per Litre:
Gasoline (Average from March/2013)
2.763 BRL = 0.938 GBP
And Ethanol (Average from March/2013)
1.944 BRL = 0.660 GBP
On the New Jazz (GE) my average on Gas is 12km/l and on Ethanol 9,5km/l but it really depends on traffic conditions and specially how you drive it.
It's a good thing that we can choose which fuel to use based on the price. There is no need to use only gas or only ethanol. It's possible to mix them at any proportion.
The only "inconvinience" is to fill this Subfuel tank, but it lasts like 6 months on average. (Starting the engine 4 times per day, considering the route Home-Work-Work-Home).