CREATE TABLE "w109" (
  "model" text,
  "chassis_code" text,
  "production_time" text,
  "number_built" real,
  "engine" text
);

Question: What model has a number built smaller than 6.526, and the Chassis code w109.015?
SQL: SELECT "model" FROM "w109" WHERE "number_built"<6.526 AND "chassis_code"='w109.015';