[KennyBlanken]

They're not "non-functional" at all.

They reduce wind noise, increase mileage particularly in colder weather (and speed up engine warmup time), protect the engine from road debris/road salt/water, and reduce lift generated at highway speeds.

"Trapping heat in" isn't a problem in almost any modern vehicle.

[rootsudo]

There's an engine cover, and a cowl cover - the one on the bottom is good, the fake plastic trim on the top is worthless.

https://www.forgemotorsport.com/Hyundai_i30NVeloster_N_Carbo...

this is worthless, and better to keep it off.

[selykg]

Person I responded with said engine cover. That’s the shit plastic they put on the top of an engine. It traps heat. It’s literally worthless.