I only have around two tanks through the car so far. And it does seem to be improving as I go along. I'm now at 6.2 l/100 average

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I am also running regular fuel in mine (87 ocatane). We live at an altitude of about 3500 to 4000 ft, so the premium fuel on the regular non-turbo engines really doesn't add much (IMO), and in my personal tests, I get better mileage on the regular fuel then premium. That may be different at sea level though.