Steven here, just back from a long weekend in the Lake District.
The scenery was fantastic, especially when the sun came out while we were climbing up Heron Pike.
The round trip was a little under 600 miles by car, including a couple of excursions.
I started with a full tank (55l) and 2 bottles containing 10 litres each - all of the fuel was filtered waste vegetable oil from my local indian take-aways. Nearly all of the fuel was used up, and I arrived home with the reserve light on. The car behaved almost faultlessly (there was a tiny issue with the fuse for the electric windows, but I swapped it for a spare).
While I was away, I got a call from a restaurant in Enfield that has some waste oil to be collected. I'll pick it up in the next few days...