We failed. After 781.8 miles, we pulled into a layby off the A42 a couple of miles from the start of the M42 southbound having decided enough was enough, and reached for the emergency five litres of diesel.

The fuel warning light had come on almost 100 miles earlier, and the range had dropped down to zero some 20 miles before we finally ground to a halt.

So with more than 200 miles still to travel on what the VW Golf BlueMotion had in its fuel lines and any hidden depths of its fuel tank – the heavens being still well and truly open – and the prospect of stopping on a sodden motorway ahead, we decided the safest thing to do was to fill up in the relative safety of a layby.

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Or we bottled it, in other words. Bottled it with a deeply impressive average economy figure (according to the trip) of 82.6mpg, achieved in 15 hours 47minutes at an average speed of 50mph. 

Now for the excuses. It was wet: very, very wet. And it was very, very wet for almost the entire trip, save for about 20 minutes of sunshine yesterday going past Liverpool. Strong winds were another issue, especially heading south today. We saw an economy figure as high as 85.9mpg yesterday, but it dropped to 82.6mpg today.

The weather made the trick of slipstreaming lorries very tricky as the spray made it hard to see, especially in the dark. I stopped short of any other eco tricks such as taping up gaps and over inflating the tyres, as this doesn’t really prove anything about a car’s capabilities off the shelf.

This was all about careful use of the right foot and reading the road ahead. 

I knew from previous experience in attempting 1000 miles in a Seat Leon Ecomotive last year that there was 75 miles of range left when the indicated range and needle both read zero, allowing me to travel 925 miles on a tank. So using this shaky logic, the Golf had about 850 miles of range available in these conditions on a sole tank of diesel.

But the plot thickened somewhat when we came to refuel the Golf; having burned off an estimated three litres (driving a bit quicker than 50mph…) on the way to a fuel station, the tank was full to bursting after 40.97 litres from the black pump.

So again using some rather shaky maths (forgive me, I’ve no calculator to hand and can only see the back of slow moving lorries in my head…), our 781 miles were covered using around 43 litres of diesel. Say the reserve was seven litres, then to use that at the same average economy figure we’d have managed an extra 125 miles when the range dropped to zero, pushing us above 900 miles.