It was some US-made SUV (Ford or GM, can't recall which one) with fairly high clearance - I specifically booked it so that I can go everywhere (Waipio, Mauna Kea etc.). The road to valley was fine, it was also dry and the only possible issue could have been crossing a few streams at the bottom of the valley, but SUV had no problem there as well (clearance was sufficient). I experienced far worse roads on Tenerife while blindly following a route computed by then NOKIA maps that took me to super steep straight-up roads where my car ended up spinning all wheels unable to move up ;-)