Petrol Vs Diesel

[Dr Jekyll]

How much of the extra mileage you tend to get from diesel fuel is down to a litre of petrol weighing around 700 grams, while a litre of diesel is about 900 grams?

How does the amount of energy compare?

[Dr Jekyll]

Flibble said:

The heavier weight of diesel would make it have worse mileage surely, as you're carrying more weight. Aside from that weight is unrelated as it's distance travelled per volume of fuel, not weight of fuel.

No, because you are getting more diesel in a litre than you get petrol. Another way of asking original question would be 'If we bought fuel (and measured consumption) by weight instead of volume, how much advantage (Miles per KG) would diesel have?