Join Date: Sep 2005
Location: English Midlands
Re. your info display problem.
Check that the system is showing imperial units rather than metric. The ration 50 to 82 you quoted is not far away from the difference between miles and kilometres! The conversion factor is 1.609344. For example, 50 miles = 1.609344 * 50 = 80.4672 km
On the GT you can alter the display parameters. I'm not familiar with the 156 but assume the same thing is possible.
Hope this helps.
My GT JTD 1.9 has shown an average of 40.85 mpg for the 54000 odd miles since I started driving it. I brim the tank and check the odometer to get the figures. On the motorway it can give about 58mpg or above, but around town the consumption is relatively heavy (around 30mpg? I haven't checked). There are probably good reasons for this. Ones I can think of are
Power steering increased use (more corners), and added friction on corners due to a relatively heavy vehicle on wide tyres
Engine stays at less efficient rpm for more time (ideal speed for a JTD is the maximum torque speed of 2000 rpm)
More braking & acceleration (wastes energy)
More idling without moving (traffic lights etc)
Engine fans sometimes cut in, using energy.