Ethel's right.
Up to the start of the nineties, diesel used to be about 2/3 the price of petrol - that was why diesel cars were so economical to run, provided you did not mind the sluggish performance.
When turbo diesels started appearing in the mid nineties, people were attracted by the economy of diesel, coupled with exceptional performance.......... until the powers that be cottoned on to this and hiked the price of diesel to rake in more money from us.