Translation:The car that was on the street was red.
Yes, in the Duo sentences we never know the context, but usually this type of situation would be imperfect because as rspreng says the car was there, maybe still is, we don't know, but most likely it just wasn't there one instant and then disappeared which would be preterite
Thank you for the explanation. Makes sense to me now. You deserve a lingot. I have done this sentence over and over ... just seemed to me that the car was on the street and now it is not. Like you say, not a lot of context. So I will stop worrying about this sentence and why it did not make sense to me using 'estaba and not estuvo'. Gives me peace of mind. LOL!
Joshua.mcf - you would be wrong! ; )
Technically, "that" is used in restrictive clauses, and "which" is used in non-restrictive clauses. Restrictive means the information is necessary for meaning, whereas non-restrictive means you can leave it out.
In this example, it is the car that was in the street that was red--as opposed to the car that was in the driveway, for instance. If the location of the car is not important, you could say, "The car, which was in the street, was red." Note that the words between the commas could be removed without changing the fact that the car was red (see Winmar's comment above).
But as wazzie noted above, most people don't know when to use that and when to use which, so they use what sounds best to them (which is subjective). You'll be understood either way, but please don't say "'that' is actually less correct than 'which' in this case," because it isn't true.