When your car smells a little off, it's trying to tell you something. Bad car smells often indicate that something is wrong and put you on the right track to figuring out exactly what is it.
1. Your brakes or clutch needs attention -> harsh, acrid smells typically mean that either brake or clutch material has been burnt. Riding your brake or leaving the parking brake on are both great ways to make your car smell like this, of course, a stuck caliper or frozen parking brake cable can also do the job for you. A burnt clutch smells similar to beprake pads that got too hot, and it can be caused bupy riding the clutch. It can also mean that your clutch is slipping, either because it's worn or it needs to be adjusted. In systems with hydraulic clutches, a slipping clutch can also indicate a problem with the hydraulic system.
2.you have an oil leak -> when oil drips on any part of the exhaust system, MIT burns. This smells really bad, and can also create copious amount of thick, blue smoke if leak is bad enough. The fix is simple enough. Get rid of the leak.
3.Your catalytic converter is busted -> catalytic converter are emissions control components that alter exhaust gasses to reduce harmful emissions. When they don't work right, you sometime ends up altering exhaust gasses to smell like someone spent most of last week throwing rotten eggs at your car.the fix is to replace the catalytic converter and also repair whatever caused it fall,assuming it didn't just wear out.
4. Water is getting where it doesn't belong -> a moldy or mildewy smell indicates that water is getting in your car to and then pooling there, leaky door iPod window seals can throw water in,so if you find wet seats or carpeting, then that's probably the issue. However, the A/C evaporator is very common cause of this particular odor.
Your Groceries rolled under the seats -> most of the reasons a car can smell have to do with some mechanical breakdown or failure, but there are a lot of outside sources as well. Before you take your car to your favorite mechanic to ask why it smells like death in there, make sure to check under seats.