Sounds like what happened to my daughter last week, she drove to work and called me right away, smoke coming from the wheel wells, Turns out she drove thru a puddle of water and it was just burning off the engine and brakes parts. One of her co-workers went to double chek for her.
It could also be a plastic bag or something of the like, Check your hoses in the engine and under the hood and engine compartment.
It smells like something on fire? like? rubber? paper? oil?
More than likely it is as Caymen and ToddZ and Me stated and just needs a good rinsng or cleaning.