No Stupid Questions

Regular gas cars should sound like normal muffled engines (comparable to your experience with 15+year old SUVs). Outside slight improvements in cabin isolator material which can dampen or lessen road noise and exhaust noise, they should sound roughly the same.

The injectors can sound like loud clicking or tapping occasionally, and depending on the make/model it can be quieter but usually audible inside the vehicle when at drive-thrus or when idling.

Hybrids usually turn the engine off at stops/low speeds and can often have a brake pedal that people complain feels spongey or loose, but due to how hybrids work that is normal since they use the electric motor more than the actual brake pads to stop in most cases. So hybrids usually have brake pads that last a really long time compared to non-hybrids.

Definitely shouldn't sound loud unless it has some aftermarket exhaust or the cat was stolen.

Depends on the car. If you've heard a 4 cylinder you've heard most of them. GDI engines have loud ticking fuel injectors at idle, this is normal, they're squeezing 600-2000 PSI of fuel pressure into the combustion chamber. Unfortunately, while a lot of modern cars have 4 cylinder turbos now, they are almost all smol turbos that spool at 2000 and run out of breath past 4000. They also don't make any cool turbo noises.

Engine will turn itself off when you come to a stop and it's warmed up. Don't worry, EV motor will get you going while the engine restarts. Lots of stop-start engines will start up as soon as you let off the brake pedal and be good to go by the time you move your foot over to the gas.

Also, engine may stay off for a bit depending on your driving mode and speeds. This is good, especially with a PHEV (Plug-in Hybrid Electric Vehicle), which has a small "for around town" battery it can drive on. Saves you in gas to charge it on the wall for those <40-mile grocery runs. Can also save you a gallon or two on longer trips by running on battery for a few before firing up the engine.

A lot of modern cars also play fake engine noises through the speakers so people who are allergic to the sound of a quiet car can pretend they have a V8 under the hood.

If you want a car that still has an angry growl but is good on gas, get a Subaru. Still a very "personality" car in this day and age, even with a CVT and a hybrid drive system. She makes lots of noises and demands your regular maintenance care (on-time oil and transmission fluid changes, regular oil level checks and topoffs if needed), but will last a long, long time if you do.

If you get a plug-in hybrid then low speeds might also have a pedestrian safety sound which is a humming that gets louder until 24 km an hour which is when it will shut off because the car road noise is then loud enough to be audible to pedestrians.

Quiet normally. Besides the fuel injectors which is 90% of what you hear in a modern direct injection car.

Direct injection engines sound like a tractor at idle.

Ford eco boost cam phasers sound awful at cold start.

We’re at peak performance and efficiency for gas engines right now and they don’t sound like older engines.

Most main stream, dare I say appliance cars, have what is called a rattly ass 4cyl. Not to be confused with nice sounding 4cyl engines.

I've also noticed new cars sound bad.

Copper coil squeak. No, wait, those are EVs.