Interesting follow up, Jon. Which follows on from an interesting drive back I had this afternoon from visiting mum.
For those who know it, we were heading North from Alton to Basingstoke. Just after the 'waterworks' bend (after the final 'left', before the 'right'), a BMW Z4 caught us up fairly rapidly, followed fairly closely, then eventually overtook. As it happens, we then followed him [assumption] all the way to Blazingsmoke, until he headed into the distance along the ring road. A minute or two later, he overtook us on the final section of dual on the A339
However . . . we were both caught behind some duffer [assumption, for comic effect] in an Audi, who did (variously) 30 in a 40 and 60 in a 50, did 'random' braking, yada yada. Oddly, BMW man didn't overtake in a place where I probably could have in the Ibiza 3-up . . . ::)
I was comfortable just sitting back 100m and letting the fuel consumption read out click ever better. BMW man, though, kept hustling up close behind whichever car he was following (first me, then the Audi) and, as a result, missed two good overtaking possibilities (he finally did go 1/2 mile before a two-lane section . . . ).
I'm not claiming to be 'better than either BMW or Audi, but I accepted that Audi's driving was 'below par' and adjusted accordingly. Mr BMW didn't. Now, if that meant he was getting in any way frustrated (it's an 'if', for the long-winded purposes of answering your question), might that have adversely affected his subsequent decision-making? Audi driver may well have been licking the glue on the edge of his performance envelope - but staying safe relative to hazards ahead - but BMW driver could have been failing to deal with that.
Your 'standard' is how you drive alone, not how you drive during a test.