Table schema:
CREATE TABLE table_name_1 (engine VARCHAR, rounds VARCHAR, driver VARCHAR, tyres VARCHAR, chassis VARCHAR)

Question: What engine was used during the race driven by Jan Lammers using a chassis of d3 d4, making a tyre of g and rounds of 4-6?
SQL: SELECT engine FROM table_name_1 WHERE tyres = "g" AND chassis = "d3 d4" AND driver = "jan lammers" AND rounds = "4-6"