What is the most efficient petrol car for under £6000?

Just wondering what is the most efficient petrol car or petrol hybrid if its better for less than £6000. I saw a 2023 post however not sure if new vehicles have come on the market.

What are the advantages of hybrids compared to petrols and EVs?

Can you tell me please the advantages of buying a self charging petrol car over a straight petrol engine car or full electric car?

I only do around 1000 miles a year - would a hybrid suit my needs?

My current car is a BMW 320i, bought new in 2014 and has 12,800 miles on the clock. Would my usage suit a hybrid or would the battery be a problem with such low mileage?

How long is it before diesel cars are banned from towns and cities?

How long is it before diesel cars are banned from towns and cities? I am 75 and need an automatic estate for my next car.