What are the consequences of accidentally hitting someone with a car, and does this entail harm, especially given that the person remained standing after the accident?

You erred by leaving the injured person; you should have sought his forgiveness and taken him to the hospital. You are obligated to pay expiation and blood money if you believe he died. If you can reach him, you must do so, because the rights of creation must be fulfilled or absolved, as the Prophet (peace and blessings be upon him) said: "Whoever has wronged his brother concerning his honor or anything else, let him seek his forgiveness before there are no dinars or dirhams [i.e., on the Day of Judgment]." If you cannot reach him, you must repent. If you believe he died, expiation and blood money are incumbent upon you. The Permanent Committee has issued a fatwa (definition) stating that whoever believes an injured person died due to his actions must pay expiation for accidental killing (freeing a believing slave or fasting for two consecutive months), and the blood money for the injured person, which is paid by the 'Aqilah (male agnates). If this is not possible, he must pay it to his heirs or give it as charity on their behalf if they cannot be identified.