I do not know if this device has been mentioned on the forum before, but it could save someone a lot of money.
When I was waiting at the checkout in Halfrauld's today I noticed a device on display called "Think Diesel". It is a small self contained unit that sticks inside the fuel flap. Opening the fuel flap triggers the light sensor switch which plays an audible message reminding you that your vehicle is diesel . May be a bit of a gimmick , but could save a big bill.
Google "Think Diesel" for details.
I have no connection with the company but think that it could be a usefull device.
The Ships Cat
I might test that out as my OH has gone to put petrol into a diesel car already