Its true that the ethanol content can vary a fair bit but if the tune is safe on the highest content of ethanol eg united stuff can go up to e90 anything thats got more petrol in it eg e70 etc your car will only run richer which wont hurt your engine anyways. Mate speak to Yavuz at unigroup engineering give him your car and never worry about ethanol content or any of the other rubbish these other "tuners" have been feeding you
Hes tuned both my cars both drive amazing have great fuel economy and have NEVER died