I know diesel cars heaters are not so good, but my cars taking around 6 miles driving at about 45 mph at 3 degrees C to blow hot air, and about 8 miles to reach a normal mid range gauge temperature, are yours ? Also there seems no way of getting both cool air on ones face and warm air on ones feet, no matter what setting I seem to use, handbook says it should be possible with lower and face vent buttons pressed ? On a long trip I often end up opening the window. Any suggestions ?