MPG  -  Car petrol consumption monitor

by Steve Hunt

Monitoring your car's petrol consumption can give an
early indication of fuel system or ignition system
problems, as well as telling you a lot about your
style of driving! MPG is an application that makes
keeping track of your car's fuel consumption easy
for you.

Running the item from the RISC User menu system, or double-clicking on the !MPG application icon (a top-less mini) in a Filer window installs the application as normal, and also opens a directory containing two example files (see below).
Clicking over the icon bar icon will open the main
MPG window.

Data within this window is presented in 3 columns:
Distance, Fuel and Consumption. The units can be
selected from the main menu as Miles or Kms, Gallons or
Litres, and Miles per Gallon (MPG) or Kms per Litre (Kpl).

When you first use MPG a starting mileage of 10,000
will be displayed. You should use the menu options
to reset this mileage to the current mileage of your
vehicle, and to select your preferred units. At
start-up, MPG will default to Miles, Litres and
MPG, but you can change this default as described
later.

When you next fill up your vehicle with fuel, note
the new mileage and the quantity of fuel used. Enter the new
mileage into the writable icon at the bottom left of the
window, press Return and enter the fuel used into
the other writable icon. Press Return again; MPG
will then calculate the fuel consumption and display
it in the adjacent icon. You will be warned if the
new mileage is not greater than the previous
mileage, or if the fuel consumed is zero. You can
then add this new record to any previous records by
clicking on the Update icon. Once you have entered
a number of historical records in this way, the
topmost icon will display the total distance
travelled, the total fuel consumed, and the average
fuel consumption for all records.

You can highlight individual previous records by
clicking over them with the Select mouse button,
or you can highlight a range of previous records by
clicking Select over the oldest (top-most) record
followed by Adjust over the newest (bottom-most)
record. The top icon will then display the distance
travelled, the fuel used and the average consumption
for the highlighted records; the figures will be
displayed in red to remind you that they refer only
to a subset of the full historical record. This 
feature is useful if, say, you want to compare the
fuel consumption achieved over the most recent 1000
miles with that achieved 10,000 miles ago.

Selected records may be deleted either by using
the menu option, or by <Ctrl-X> if MPG has the input
focus; however the Delete option is not available
if all records are highlighted. The highlighting
can be cleared by clicking Adjust over the top-most
highlighted record, or from the menu.

Historical records can be saved using the menu Save
option which operates in the usual RISC OS manner.
If you wish to alter the default units used by MPG
at start-up, and you feel confident about editing
Obey files, you can alter the line in MPG's !Run
file that sets the MPG$Opts variable. This variable
consists of the letters F, D and C, each followed by
a 0 or a 1, which have the following meanings:

   F0=Gallons
   F1=Litres

   D0=Miles
   D1=Kms

   C0=Miles per Gallon (MPG)
   C1=Kms per Litre (Kpl)

So, for example, F0 D1 C0 would mean we wanted to
use Gallons, Kms, and MPG.

Two sample files are included to give you an idea of how the program works. These are entitled Golf and Mini and are located inside the !MPG.Files directory. These files can be loaded in the usual way by double-clicking on them or dragging them to the application's icon bar icon.

Copyright  RISC User 1996
