Getting ready to purchase a 98 2.8 Z3. Wow, I can't wait. My only concern was maintenance costs, but after checking around, my worries have been put at ease. I didn't really understand the green bar system, but in reading on another thread have learned that one green bar is equivalent to 1200 litres of gas, or approx. 317 gallons. So if I understand correctly, if I have 3 green bars, I should have about 16 - 17 thousand miles of useage before maintenance is required (assuming 22 mpg). Can anyone verify that this is correct?