SELECT MIN("Year") FROM table_69441 WHERE "Power" = '90kw (121hp) @ 4000'
When is the earliest year with a Power of 90kw (121hp) @ 4000?
CREATE TABLE table_69441 (
    "Engine" text,
    "Displacement" text,
    "Power" text,
    "Torque" text,
    "Year" real
)