For months I had to drive my Yarris up and down a pretty rough track - no gravel, full of potholes, just hardened earth and stones.
The Yarris with its little go-kart wheels handled it like a champ, even if I'd bottom out almost every single time. Even climbed up it fine provided you kept it above 25km/h all the way :) Took to a mechanic later and he said the suspension and undercarriage were fine.
Really wish we could have gotten a decent GT version in the US. But Toyota is what Toyota is.