<Tr> <Th> Compound </Th> <Th> Petrol </Th> <Th> Diesel </Th> </Tr> <Tr> <Td> nitrogen </Td> <Td> 71 </Td> <Td> 67 </Td> </Tr> <Tr> <Td> carbon dioxide </Td> <Td> 14 </Td> <Td> 12 </Td> </Tr> <Tr> <Td> water vapor </Td> <Td> 13 </Td> <Td> 11 </Td> </Tr>

Motor vehicle exhaust is a source of which odorless