I'm wondering if fuel from the supermarket or premium brands or premium fuel or higher octane fuel makes a difference in either performance or mpg for the 659cc JB-DET Copen?
In my experience, if you put 95 octane (5% ethanol) in it will be fine, regardless of what brand it is, as the engine is made for 91 octane. At least in germany there are standards for fuel that every brand has to abide by, so there are no surprises There is one brand named Aral (owned by BP) in Germany where I seem to notice a slight, but negligible difference. I have the impression that the car runs smoother with their fuel.
A couple of times I've put 98 Octane in, because I was testing a friend's theory that you get more "bang for your buck" in terms of mileage from 98 than from 95. (My figures said otherwise) HOWEVER, I felt that the car ran better and had more get up and go, when it was running on 98. Fuel here in Australia has always had a price cycle, and I feel that lately, fuel distributors seem to have forgotten about the "down" part of the price cycle!! We are paying upwards of $1.50 a litre at the moment. I can't remember the last time I filled the car, preferring to just put enough in the tank to get me around, in hopes that prices will fall. Pfft.
It is on the rise at the moment for us as well, see the chart I have half a tank left, so I will wait, maybe prices will drop well below 1.40€ (2.20 AUD) for Super E5 fuel again
FWIW I was using 95 E10 for almost a year after I got the car, until I heard that Daihatsu doesn't recommend using ethanol at all. So, I changed to normal unleaded, and immediately noticed I was going noticeably further on a tankful. I wasn't sure if there was any difference in performance, but I'm ahead financially, because the straight unleaded is only 2 cents/litre dearer than the E10.
