No its my own private van, I'm now a sole trader.
But in previous lives when i did have company cars i was the same, felt over a tank full of fuel the difference was only a couple a quid or so and wasn't worthy of my concern even though i was doing 30-40k miles a year.
To be honest i never look, the fuel light comes on telling me i need fuel so pull in the next station and fill up.
I never look at what the cost is as i just need it what ever it is.
One thing i do hate when filling up "do you have a Nectar,club/loyalty, FU@K OFF, hate all these with a passion.