Volvo AWD and Subaru AWD

Its not trolling at all. Perfectly valid question.

I imagine it is, but to be honest, I wouldn't know where to find it. Most of the stuff around has to do with side-by-side comparison on ice, snow-covered tarmac, and dry cold road. All-seasons don't fair well on any of those.

They don't need to back up the claim. If it reduces the life of the engine, it costs you money. If you get fuel consumption that is worse than on the recommended, then it costs money. I have never had to change a high-beam bulb on any car that I had DRLs on (and I generally keep them six to seven years). Its all false economy.

The only thing that keeps any driver from disaster is good brakes and good tires. I prefer not to compromise on either. Its false economy; just like getting crappy gas mileage by using lower grade fuel.

Of course it does. If the engine is knocking, it is causing damage. And if the timing is retarded (which it will do when knocking) gas mileage is worse; if your mileage drops by 2MPG, its cheaper to use high test.