Is there anyway this isn't gross incompetence by Chevrolet of GM engineers?

To expand upon that, if parked facing the downward slope, the front wheels should be turned toward the curb.

If parked facing the upward slope, the front wheels should be turned away from the curb.

Otherwise, in each case, if the wheels are turned the opposite way and the car rolls, it’s curtains.

Doesn’t San Francisco (and maybe other cities on hills) have a “Curb your wheels” bylaw? If so, they probably date from the '20s when runaways were more likely (and cars had curtains).

the car in question is 10 or 11 years old. We don’t know how many miles it has or how heavily it has been used. It’s not inconceivable that something might wear out or break on a 10 year old car. Except, perhaps, to someone who can’t even be arsed to know what company made their car.

NO. Front wheels always towards the kerb. Upslope or downslope don’t matter. Always towards the kerb. If upslope, the BACK wheels hit kerb, if downslope it is front wheels. Try it next time. (I got this wrong 20 years ago when sitting my license).

Since the subject of manual transmissions, parking brakes, and cars that don’t stay put:
http://boards.straightdope.com/sdmb/showpost.php?p=7575292&postcount=9

In California, you’d have been correct the first time. It shouldn’t really make much difference which way you do it. The front wheels will hit the curb if you turn out facing the upslope; the back wheels will hit the curb if you turn in facing the upslope.

An American-made car that I had in years past allowed me to start the car and remove the key. I could drive without the key in it. However, it did need the key to turn the ignition. I was told that the key-lock mechanism was worn down and needed replacing. The car was a rust-bucket, so I didn’t bother with the expense Heaven help the person who would want to steal my Gremlin!

In a car that old, the key barrel can become almost completely smooth, so you can start it with an appropriately sized screwdriver. It happens at about 7’00" in this Top Gear bit. Obviously, that would include the latch that keeps the key in.

can we keep the discussion centered around cars which weren’t made 40 years ago?

Sure. The car I am referring to was only 8 years old when this unadvertised feature became available. My story was meant to show that a car that is not new, may have parts worn down enough to cause surprising results.

Maybe the OP’s car wasn’t completely in Park. Or it was, but a mechanical part gave out. That doesn’t make the manufacturer horrible. The fact is parts wear out. That’s why manufacturers recommend regular servicing.

I was taught the opposite. Maybe the difference involved the length and width of cars in North America vs. the U.K.

For instance, an everyman’s '59 Chevy, 17.5 feet long and 6.6 feet wide, would stick out a long way into the road before the rear wheels hit the curb on a downslope, especially if the car had been parked two feet or farther from it. Some cars were bigger than that, and downsizing (some would say such as it is) took decades.

Even now, full-size SUVs would present the same problem.

My 2001 Chrysler Sebring convertible had the exact same problem – and it developed over time. It started with letting me turn it off and pull the key out when it wasn’t in park. Then eventually the lock got loose enough that I could remove the key while the car was running, and it would continue to run (So much for chipped keys, huh?). This became especially problematic going around curves, because the keys would often fly out and wedge themselves somewhere underneath the passenger seat.

It also would shift into “almost park” where it looked like it was in park but the pawl wasn’t engaged.

Sounds like Sebring owners should investigate whether there are secret warranties on ignition switches and transmission linkages, or even not-so-secret recalls.

Just as a minor data point, there are a couple of TSB’s on the 2002 Chrysler Sebring automatic transmission. One of which may be pertinent to the OP.

http://www.chryslerproblems.com/tsbs/Sebring/2002/