So at lunch on day one at Chorley Services, the mighty Seat Leon Ecomotive has covered just over 220 miles. Just looking at the fuel gauge – which sits between three quarters of a tank and full – would indicate we'll get back to Teddington tomorrow with just under half a tank left.

But of course, that's not going to be the case. Looking at the trip computer – and I’m still trying to work out if it is my friend or not – it would indicate we'll run out of fuel just past Birmingham on the way back.

The range is just under 700 miles, but as recently as 25 miles ago it was telling me I had 775 miles left. Economy took a hit in torrential rain on the M40 this morning, dropping from the 72mpg indicated in the early stages of the M25 to around 65mpg.

But some speed restrictions on the M42 and the ability to go at my own pace on the M6 Toll and subsequently deserted – and flatter – section on the northbound M6 has recovered it to around 72mpg.

A few things I've learned so far: the Leon’s tank is greater than 55 litres – I squeezed 55.something in it this morning when it was still showing a 50-mile range.

Next, my right foot must not move from its fixed position. Any movement, especially uphill, makes economy take a nose dive. Brakes are also a no no, but I've only pressed it four times: oddly, twice for badly driven Nissan Micras, once at the M6 Toll and one just now at Chorley.

My biggest enemy will be the rain. It made a noticeable difference on the M40 and has just started up again as we head further north. Whatever happened to that famous northern January sunshine?