Mi carro no arrancará (o prende), pero cuando enciendo la ignición oigo el motor de arranque girando.

As you can see, language in Spain sometimes is pretty different than in latinamerican countries. I think it happens the same with English. "Car" in Spain is "Coche", but in South (and Central) America people call it :"Carro" or "Auto". In Spain "carro"="carriage". On the other hand, "auto" means "car" in both "spanish languages" but in Spain, its use is very uncommon. ---"My car starts"->"Mi coche arranca" or also "Mi coche enciende". "Start" when you talk about an engine is translated by "arrancar" or "encender" ---"Turn the ignition"->In this case you should say something like "Girar el contacto" or "Dar al contacto". ---In spanish if you speak with a person who knows about cars, as you can see in this link: http://www.wordreference.com/definicion/starter , you can use "starter" So the sentence could be something like this: "Mi coche no arranca, pero cuando le doy al contacto (also "cuando le doy a la llave"; "cuando giro la llave"; "cuando lo enciendo"), puedo escuchar ("oir" is right too) el motor girando ("el motor funcionando")

According to your explanation, I would say something like "Mi auto no parte, pero cuando enciendo el arranque escucho el motor andando" By the way, car has many translations into Spanish, depending on the region. In my country we say "auto", but you can also say "carro" or "coche". Saludos!

Hey Adam, I am going to say to you how we wouldsay that in Spain.it is a bit different from the others, so you take whatever you want :) Mi coche no arranca pero cuando (giro o doy) al contacto, puedo escuchar el motor de arranque funcionar

You can say: Mi carro no arranca. El motor de mi carro no arranca .