Generate cost per mile on a per garage basis - allowing for comparison of fuel economy between different garages.
Needs to be carefully implemented though as the metric that needs to be used is the distance between the current and the next fill;
From the table above we could calculate
|Tesco|1 mile per litre|£1|
|Shell|2 miles per litre|75p|
|Texaco| - | - |
i.e. after filling up at Tesco's, a journey of 10 miles required us to put another 10 litres in the tank. The fuel we bought at Tesco's was £1 a litre (I wish) therefore
(10 miles / 10 litres) * £1 = £1 per mile
May be tricky to generate monthly per-garage CPM stats as it's unlikely that all recorded garages will be used each month - an overall stat is probably the better move.