As I have often written, the fuel gauge and the mpg figure is a work of fiction. The first day I had the K12 I ran out of fuel with the computer saying I had 47 miles left so that fuel gauge got replaced under the dealers warranty.
I soon started a spreadsheet to keep a record of the bikes history and realised that I was filling up well before the tank was empty. I kept pushing the distance I rode until on one occasion I did 38 miles after R=0. One extreme to the other. Hey, big UP! for German technology. The computer mpg number was averaging 8% optimistic.
Suddenly after almost exactly a year and weirdly coinciding with a tyre change, all things changed, I have no idea why. Fortunately I was doing a regular commute and had regular stops. Instead of being able to ride way past R=0, I noticed the spreadsheet was calculating that I'd be lucky if I got 5 miles.
Another 18 months and I was regularly riding until the range was below 10 miles and confident I had fuel left. I did the fuel tank filler neck mod (drilling air holes into the neck to more easily squeeze more fuel in). A couple of months later things went wonky again and I ran out of fuel a few time, fortunately I was working at Hinkley Point and its pretty flat around there so easy to push the bike. I say easy, that's in terms of meaning I could actually push the bike without expiring after a 100 yards. After a few weeks a kinked breather pipe was diagnosed. Basically from then on, if the range says zero, its zero.
Another year went by, no issues, computer 7% optimistic. Interestingly on a 1100 mile trip into Germany using the 100RON fuel the computer was accurate to 1 or 2%, and after that it stayed 3 or 4% accurate while I ran around Holland for a few more months on 99 RON.
In the first year or so of lockdown the accuracy was 6%. After I had all the work done on the suspension and replaced all the bearings etc, and in the second year of lockdown, its now at 4%. I don't know why its improving but I just know when I look at the computer data what the real numbers are. If anything my riding is much more varied than it used to be when commuting.
Moral of the story do not trust either your fuel gauge or the numbers in the computer. Work it out by keeping notes of your mileage and your fuel receipts, and try to completely fill your tank every time. My average fill up range over 478 tankfuls is 178 miles with a best of 219 (well I had just been banned for a fortnight and fined £LOTS so was trying to be a good boy), and the lifetime average is 43.02mpg.
Other exciting statistics: Average speed to date is 53.5mph over 84811 recorded miles so that's 1585 hours in the saddle. Cost is at 44.6p a mile, and that includes all the money I have spent recently on renewing suspension exhaust ABS pump panniers, so that number is now dropping again as the miles clock up again. If you include the purchase price its 51.5p a mile. Of those numbers fuel contributes 14.1p a mile.
