I had this same problem, My tuner scanned it and turned out to be the crash sensor in the front bar had a bad earth, bit rusty between the sensor and body. Bit of sandpaper to fix, all good now
Just drove to the Gold Coast and back Best I could get was 9.5L/100km, and that was giving it a bit on the occasion It is more economical than stock which was (10.5L/100km)