There is a significant chance that if you assert your rights you will shortly be let go and if you let them search it will be a lengthy process. There is a non-zero chance that evidence is planted during a search. If you or any of your passengers (present or past) are drug users there is a non-zero chance that legitimate drug residue is in your vehicle. If you purchased your vehicle used there is a non-zero chance the previous owner left drug residue in it.
In my opinion having a police officer search a vehicle is more risky than asserting your rights.
There is a significant chance that if you assert your rights you will shortly be let go and if you let them search it will be a lengthy process. There is a non-zero chance that evidence is planted during a search. If you or any of your passengers (present or past) are drug users there is a non-zero chance that legitimate drug residue is in your vehicle. If you purchased your vehicle used there is a non-zero chance the previous owner left drug residue in it.
In my opinion having a police officer search a vehicle is more risky than asserting your rights.