High Fuel Consumption on the highway
I'm new to the forum and had a bit of a search around but couldn't find anyone else mentioning this.
I have a 2011 Manual Diesel 420 Highline. My fuel consumption around town is outstanding at about 8L/100km, but on the highway at a steady 110 km/h it is significantly higher and usually around 11L/100km.
I've checked tyre pressures, wheel alignment and using an OBDII plug Fuel Rail Pressure, Boost Pressure and Coolant Temp. The coolant temp was struggling to get to 75C even on a hot day, so i thought this might be the problem. Mammoth job to change the thermostat and now runs bang on 90C but the highway fuel economy hasn't improved.
I'm suspecting the DPI filter may be nearing the end of its life at 230000 kms but haven't had any error codes or warning lights.
Has anyone else come across this problem?