I'm trying to think of 'overrated' - a tough one as so subjective with looks etc. And not just saying a car is overrated as you don't like it, for eg with dual cabs I'm no fan of them, but plenty are, they are a good compromise between work/family/load/offroad so they probably sell for a reason.
Going back, only thing that immediately pops up is VT Commodore vs the poor AU. On sales, perception, looks, VT conquered. On the substance behind it, AU had the engineering quality while things like the Commodore
IRS needed the VXII upgrades from the start. But VT was marketed so well (interior choices, ride choice, pitched with a bit of special for everyday people user-choosing their work car etc) and AU so... ordinarily... that in respect of how they were built, the VT was overrated.
Edit: a modern example, the Hilux/Prado 2.8DPF that could lay a smokescreen like a WW2 destroyer. Hasn't seem to affected the resale, or the reliability perception.