Most if not ALL of your 'negatives' are covered by the Magnuson/Moss Warranty Act.
The simplest way to define how it covers the customer in the most common complaint/occurrence is this: The burden of proof is on the DEALER/MANUFACTURER to show WHY your failure/breakdown is not covered under your warranty.
I've dealt with these issues unfortunately a lot, and it's down-right comical how LITTLE dealership service personnel actually know about this law.
You could conceivably modify the living piss out of your vehicle, and despite what the average service writer would tell you about your mods voiding your warranty, the company he works for legally has to prove how and why said mod(s) caused the particular breakdown you've brought your vehicle in for.
If for instance you installed an aftermarket 'cold air' intake, and you bring your vehicle in for a slipping trans, or pulsating brakes, or even white/blue smoke in your exhaust, despite his urge to deny you coverage the second he pops your hood and sees the aftermarket intake, he must first diagnose the problem, then SHOW how YOUR MOD(s) caused it.
This is a FEDERAL LAW, so your own state's law(s) governing motor vehicle warranties are separate, and CANNOT cancel out/void your rights under the MM Act.
FWIW, you can find out anything and everything you wanna know about it by simply punching it into your favorite search engine