Solo: Sydney to Melbourne, 560 miles, on 2011 Christmas Eve.
Bored at work about 3pm everyone was leaving early. As an expat I had little planned for Christmas Day so decided to drive down to Melbourne to meet some other friends who were there for the Boxing day Ashes test. Ran home, grabbed a carrier bag of clothes and toiletries, jumped in the car and went. Got there about midnight and surprised my mates the next day.
Shared: Sydney to Adelaide with 2 friends, 870 miles, set off at 0915, got there at 1945 in time (30 mins time difference) to check in to our hotel and head to the bars.