How can I compare running costs for petrol, diesel, electric and hybrid?

I want to buy a used car for my company. How to work out the fuel / electric cost so I can compare?

Why does my distance to empty keep changing?

I have an MG HS and since I purchased I have had a issue with the miles in tank reporting incorrectly. e.g. I can do a motorway journey with the car showing 300 miles in the tank travel 195.5 miles and...

What fuel stabiliser do you recommend?

In answer to another question it was suggested that a fuel stabiliser could be used if the petrol engine is not much used. Any suggestions as to which fuel stabiliser?

Is a petrol car better than diesel for short journeys?

Am I right in suggesting that it's better to use a petrol engine rather than a diesel for short journeys on a regular basis for example only doing 20 miles a day and not really exceeding 50mph? I was thinking...