this happens in USA UK India where car's are expensive and people prefer buying second hand cars never heard car's in this situation here in dubai. but thank you for the awareness
If the Duct of the AC is left open there maybe a passage to let the Air in and can make a wheezing noise.
even when the windows are not rolled up properly you can hear some noise.
the accelerator can make noise too.
Did you figure out the noise from your car?
Check all spark plug one or more must not be working.
If spark plug, plug wires and ignition coil is fine then something big inside engine is gone wrong like piston ring is weak and burning oil for smoke.
Or check Air filter and Air flow meter is malfunctioning running rich fuel which make missing and smoke.
Being an older car you will have extra expense for sure. And when you offroad same it will get double.
However if you had this car from long and been taken care nicely then its very good idea to make it desert ride so you know no hanky panky shortcut job done in past. When you make desert ride its always advisable to have little lift so that you drive good and car will struggle less with higher center of gravity.
Take it to agency and let them figure out. It must be in warranty.
even if its not take to professional as this new GT-R is having very sophisticated new engineering engine and dont let monkey touch it and cause you big bucks later.