As a Tech we get asked by our customers to sometimes to perform tasks most people would not think would be in our job description. One of these things, is a complaint that might start off like " there is a weird smell in vehicle". Well people we HATE smells. To start off I would think 75% of the vehicles we work on never get cleaned or vacuumed. So lets start there. If the car is cleaned and the vehicle still smells bring it in to get looked at. Another thing if you see signs of mice don't ever I repeat EVER use poison in or around the vehicle. Mice will sometimes find a home in your vehicle, eat the poison go to there home and die. Now we have a really nasty smell, and can get very expensive. If the critter died some where in the heater vents it can cost over $1,000 dollars to find and clean these things out. Use traps. You are able to get the problem under control before its costs big bucks.
Simple things to do to save money. Clean and vacuum the vehicle. Sometimes its the left over fast food back tucked under the seat. Changed the cabin Air filter if equipped. Cabin air filter, filters the air when the heater or a/c is turned on to fresh air. Clean underneath the cowl, leaves and debris get under there and rot. The fresh air vent pulls the smell through and into the vehicle. Check to make sure the A/C evaporator drain is not plugged. Water builds up on the condenser has no where to drain so it gets musky and stinks up the vehicle. Easy way to do this is check under the vehicle after a nice drive with the A/C on if you see water dripping its most likely not plugged
If you find yourself in position were a nasty smell is inside the vehicle. Check the things in the above paragraph before taking it to a shop could save you money.