Not joking ..but the smell from your car can tell a lot..

For people who have sensitive/sharp sense of smell thsi could be helpfull:
1] Smell of burnt cardboard/paper : Your clutch is burning
2] Smell of engine oil : Either some seal/gasket is gone and spraying on the hot engine bay
3] Burnt oil : Either u have not changed your oil and its buning up or there is some issue with your engine and oil has managed to reach the hot exhaust (this will also show as white smoke)
4] Sweet toxic smell : Coolant has spilled onto something hot, probably your coolant hose is leaking or something has damaged the radator.
5] Burnt rubber : :-) You have been having fun..