We have two fairly decent diesels that do about 50mpg in the real world.
The high prices are definitely annoying, but probably put us about equal when compared to equivalent petrol cars. We've lost the advantage, but we're probably not yet at a disadvantage.
I'm talking about like-for-like comparisons - a big safe comfy car, not a shopping trolley with a tiny engine or a complicated hybrid that's going to cost more to buy and fix.
But hopefully things will return to more normal kind of price differences eventually, especially as people such as you have now shifted your demand from one fuel to the other.