Gas update?

Once again, I didn't end up getting my own gas. I wound up driving for a yard sale route this past weekend (best find: $12 for most of both Toby at Wellsworth Station and James and Percy Tunnel Set - got all of Toby and James, all but one part for Percy, the tunnel, and a ton of DUPLO track), but I never wound up heading back out later in the day (and dad - perennial misplacer of receipts - volunteered to get gas).

Here's a rough data point, based on how much gas he thought he pumped and what the odometer said when I got back in this morning (traffic was AWFUL, and I was late even without having to stop for gas).

13.5 gallons?
311 miles ?

23.03 MPG