Megalong Valley is about 30min from my home. One way in, one way out. It's very tight in sections - tight enough that I'm faster through there on a small moto than a larger more powerful moto, let alone a car. I haven't taken the XPower down
because of the tight sections. That said, there are a few lovely little stretches that would really suit the XPower. The descent to end of the drivable part of the valley is only about 16km (10 miles) and most of the footage (all the rainforest) is from the 8km of descent and flats to the tea rooms.
They scored surprisingly little traffic, too. Even on a weekday it's usually popular. I usually have to play elastic bands - catch up, stop or go really slow, catch up, stop [repeats]
Also surprising, no roadworks. Little landslips causing road closures are common.