I was easily able to drive the whole way in a stock, gas RAV4. There are a number of small water bars at the start and a couple at the end. Note you can also drive a further c. 600m of the Blowdown Pass Connector to where there were several vehicles parked. I think you could take a sedan to at least c. 9.3km, and any SUV to the end, except if very wet. It's a little rougher for the last c. 900m (and the first c. 600m of the Blowdown Pass Connector).