It's never pleasant when your car starts smelling a little on the odd side, especially since this often points to a problem beneath the hood. However, those strange smells can be to your advantage – they let you know that trouble is afoot, and they can even clue you in on what the problem is. Here's a quick rundown of common car smells and what they might mean.

1. Sweet and Syrupy

If you notice a strong, sweet, and perhaps slightly sickly smell coming from your vehicle, it's likely that coolant is leaking. Coolant contains ethylene glycol, which possesses a very sweet smell, and a strong odour inside the cabin usually indicates a serious problem. You may also notice this smell when you enter your garage in the morning. Coolant can drip down overnight, building into a puddle beneath your car.

2. Rotten Eggs

A smell of rotten eggs is typically an indication that you're driving with a 'rich mixture'. This means that the ratio of air and fuel within your engine is a little off, with too much fuel being burnt. You might notice black smoke coming from the tailpipe, and this will often be accompanied by that strong, unpleasant eggy smell.

3. Petrol

Any smell of petrol should be taken as a real cause for concern. Older vehicles used to smell a little like petrol when they were shut off after a long drive, but modern vehicles are made with tighter, more dependable systems, so this odour definitely points to something wrong, probably a rupture in the fuel-injection line or in the fuel-tank vent house. Remember, any leaking of fuel can potentially cause a fire, so visit a mechanic as soon as possible if you notice a smell of petrol.

4. Singed Fabric

This smell will usually be evident after you've been using your brakes a lot, and it indicates that the brake pads are getting overheated. This is actually nothing to worry about if you've been taking your car down a steep mountain pass or some other road where regular, hard braking was required. However, it shouldn't occur during everyday driving. If it does, one of the brake callipers might have seized up.

Of course, these links between certain smells and the problems likely to have caused them should never be used to completely self-diagnose a problem. If you notice one of them, make sure you visit your local car service shop – they'll be able to take a look inside the vehicle and check out what is really going on.