I know quite well a grandfather with a 1HD-FTE 100 series (The 1HD-FTE is the most efficient toyota 6 cyl engine ever). It has never reached 10 litres/100km and it's been trying for 200,000km. Even when driven well under the speed limit.
Your mates figures are BS. Take a look on Spritmonitor.de or fuelly and find any results which match.

