Some have something simple, like squeaky brakes or weird tyre wear, but there are others with major dramas.
Just this week I've had a Volkswagen owner who needed a new engine and a Range-Rover tragic, owner of close to a dozen of the top-end SUVs, who is heading for an all-new replacement off the back of more than 20 fruitless trips to the repair shop with his $100,000-plus pick.
Every one of these problems reminds me that cars are complex. And even the best ones can go wrong. But the cars of today are so much better than the cars of just 20 years ago that it's almost beyond belief.
The only truly bad car I've test driven this year is the Chery J1. The Chinese toddler has quality that's worse than the original Korean arrivals in Australia and, if I can pick the difference on day one, then it's going to be bad news once it's got a few years and some serious kilometres under its wheels.
Flick the calendar back and things were much worse. I still have nightmares about the press preview of the original Holden Camira.
The first 'global' car to land in Australia seemed like a good idea, but that was before the gearstick feel out in my hand. And the bonnet flew up for no reason. And the dashboard squeaked and groaned and flexed and wobbled.
Every motoring journalist has some sort of Jaguar horror story, and I recall the luxury XJ that dumped all its oil on the brand-new floor of my garage. Then there was the Range Rover that dropped both of its external rear-view mirrors - for now apparent reason - as I overtook through the shock blast of a B-double truck.
In recent year, though, the failures have been few and far between. Yes, I've had complaints about the operation of a variety of DSG gearboxes in a variety of Volkswagens, but every car has come through its Carsguide test program without failing.
Which brings me to the HSV Commodore I was once driving down the Hume Highway to Melbourne. Everything was fine through the performance runs and cornering trials, so I was dribbling home at a steady 100km/h when the engine failed. No bang, no crash, just a complete absence of power that was eventually traced to a fault on the crankshaft.
The real kicker to the story is that I was forced to take a tow to the nearest town from a motoring journalist friend who was making the same trip. And he was driving a … Jaguar.