Bro,
Cockroach is survive from Dinasour era till now. I don't think any ridsect, baygon , etc is useful. Hot weather or expose under sun doesn't work at all but in fact you yourself dying first before the extinction of roaches. Under extreme temperature benzene gas will come out from the plastic and dashboard and resulting hazardous to yourself. This same with Ridsect and Baygon. I tried it before , i have my worst day for almost 1 month as air conditon is cycling and although windows is open still had to get rid of the smell.
My method is simple and always works too. Purchase cockroach powder ( poison ) put a little here and there in your car. Leave it for 1 whole week than vacuum clean you whole car. You shall find lots of dead cockroach. Good of it, whereever you fail to vacuum those dead roach will be the meal for 2nd , 3rd batch of incoming roaches. As roaches known to canibal its own species too. Those dead roaches is dead due poison and the poison still stay too. This how it works. The cycle will continue never ending.

"1 roaches = 30 roaches hiding behind"

Finally, your car is extinct of roaches forever and ever. Anyhow, i'm not roaches king or any biological connected to it. Just sharing here. Good Luck!!!!