Yeah, they do well at cooling their base engine, but their upgraded engines, they seem like they don't provide enough room for a bigger radiator.
Didn't your tbss have head issues though? Lol.
My SS had everything issues. I replaced all the rubber, the water pump thermostat, and upgraded the radiator. Added electric fans to it as well. Bear change was moving the trans cooler to the brake duct, and taking it out of the front stack loop. Helped a little, but not enough. Finally gave up when I found the head gasket leaks. Even when I could keep coolant in it, I had to watch how hard I pushed it or it would overheat. Worst was coming off the expressway, then sitting at a light at the bottom of the ramp. Efans on full blast the temp gage would spike high.
The ZR5 was just too much motor in a tiny package. It wasn't even a hot motor, just the stock 4.3L. Went in under warranty 3 times for overheating while idling in the summer. I added a thicker radiator and efans to that one, then took the trans cooler out of the front cooling stack and put it under the bed with dedicated fan. Couldn't run the A/C unless you were moving above 15moh and below 65mph. Most guys that kept those trucks ended up with auxillary coolers for everything scattered all around the truck.
Now, the RX8 was great. Lots of people had cooling issues with those, but mine had the factory "aero kit" on it that includes a front lip spoiler. That lip spoiler kept air flowing over the radiator and the 3 oil coolers. Never had an issue despite seeing lots of others fight it.
The Q7 (aside from the water pump) has a pretty stout cooling setup. Something like 10gal of capacity, a super thick radiator, and two auxillary coolers in the brake ducts for the supercharger. I've beat and beat on it, towing in FL with A/C on full blast and it's never had an issue. Guys tow out west over the mountains report same performance.
I'm fairly certain it's a design philosophy difference. GM designs around expected horsepower draw or use assuming you hit peak power for a few moments, while Audi designs around max power produced and 100% duty cycle.
With all that said, the 5.3's in my Yukon and Sierra were rock solid and never had a single issue. Even at full send with heavy trailers, high elevation and freeway speeds. Small engine in a big truck though, so very easy to put a big radiator in there. Also, to your point, base engines in both.