Tuas - 6 lanes + a very big divider in the center. Very long and
straight.
Coastal road, along the stretch of the changi airport runway.
Jalan Bahar to Neo Teo Road.
Bt Panjang to Woodland via old woodland road.
Mandai road
Thomsan Road to Sembawang Road.
If you want long roads, go drive NSH during the night. Shoot all
the way to Kl,
420 km of roads for you to drive till you puke. lolz 
Full speed chiong @ 160 would take you around 4 hrs, including
breaks for your engine to cool down.