Travelling from North West London to Margate, Google maps suggest that I can go via the M25 in 2hr 04 min (102 miles) or down through central London and east along the A2 and M2 which would take 2hr 09 min (84 miles).
If i'm travelling at the weekend (no congestion charge) in a 1.3 litre corolla, and having to pay a £1 toll on the dartford bridge; which of the routes would you think be likely to work out cheaper in terms of the cost of petrol?