As mentioned on your other thread I came to the same conclusion and bought an outstanding 2010 example for just over £4K. Mazda 6 and Honda Accord are good options too but I’d stick with petrol at this money. You’ll get newer and less mileage for your budget and there’s far less to go wrong. These three will break 40mpg easy enough and the extra 8-10mpg the diesels give just aren’t worth the added repair and maintenance costs unless your doing a huge mileage.