Hãy thử điều này:
SELECT driver, SUM(`position`)
FROM (SELECT driver, race, season, `position`,
IF(@lastDriver=(@lastDriver:=driver), @auto:[email protected]+1, @auto:=1) indx
FROM results, (SELECT @lastDriver:=0, @auto:=1) A
ORDER BY driver, `position`) AS A
WHERE indx <= 5
GROUP BY driver ;