How about 'almost winning in a midfield car'?
Damon Hill, Hungary 1997, and Ivan Capelli, France 1990 are two of the most obvious examples. Hell, Capelli and Gugelmin hadn't even qualified in the previous race and almost scored a Leyton House 1-2! I seem to remember flicking over from the Wimbledon final and being astonished to see those turquoise cars at the head of the race...
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To be fair those Leyton Houses at the 1990 french Grand Prix were anything but "mid-field " cars, and it's interesting you should mention that race actually because with hindsight, this was the early manifestations of youthful genius from Adrian Newey, full of ground-breaking advances, but also very much a raw diamond, and that car was a perfect demonstration of it.
Aero-dynamically ahead of its time, but very perfectible and susceptible to go from one end of the grid to the other at te merest adjustment. That car had incredible downforce levels for its time and was superior to anything else in fast curves, BUT ONLY ON SUPER-SMOOTH TRACKS.
Any tracks with the merest suggestion of bumps or uneven tarmac and that beautif balance went to pieces.
Unable to even qualify in Mexico, The Leyton House was so incredibly efficient on the newly-re-surfaced Paul Ricard it didn't even need a tyre change, unlike all the other top-teams and Capelli duly took the lead when Maaccas and Ferraris pitted.
Only a dodgy fuel pump (I think it was) made him unable to stay ahead of Prost in the closing stages.
On the equally smooth (at the time) Silverstone the following week Capelli starting tenth was half-second quicker THAN EVERYBODY ELSE in the race, and that was despite a broken exhaust, and was inexorably catching the leaders in front of him. May very well have won there as well had he not been forced to retire with a broken.... something. Can't remember now.