No, I can't beat that, 406 is my best. At last years Wales meet I filled up on the Thursday, drove from home to The Moreton on the Friday (about 20 miles all on dual carriageway) returned home later that evening and then back again the next morning did both the Saturday and Sunday runs and had about 20 miles left to DTE when I got home. I did cut out the last part of Sundays run but covered in all almost 280 miles over the weekend.
Pete