There are many differences in vocabulary between different parts of the Spanish speaking world. One word with several regional variations is 'car' (as is 'automobile').
Spain - the car = el coche
Argentina, Chile - the car = el auto
Mexico and elsewhere in Latin America - the car = el carro
The more formal word 'automóvil' would be understood anywhere though. Note that all of these words are masculine nouns so would be preceded by 'el' or 'un'.