I feel like we have seen similar sentences in Duo exercises that omitted the oda. I am not sure what it adds to the meaning. Megyek implies movement, hez to the car. Maybe the oda implies away from the speaker. I don't get this. Anyone help with this?
The oda- prefix adds a meaning of "to there, to that place". It is not exactly needed in this sentence, but suggests that the store is maybe a small trip away. Also a prefix gives the verb a perfective aspect, i.e. it's not saying that I have a regular habit of going to that store, but rather that I'm on my way right now to visit it.