What is the ruling on a traveler praying in a car for a short distance for fear of missing the time, and is he obligated to stop to perform it, and what is the ruling on a passenger praying alone without waiting for the driver?

"The obligatory prayer is not valid when performed sitting in a car if one is able to perform it on the ground, for standing is a pillar of the obligatory prayer, unlike the supererogatory prayer, which is permissible [to perform sitting]. And whoever prays alone without waiting for his companion, his prayer is valid, but he has missed the reward of congregational prayer, and he may incur sin according to the opinion of those who deem congregational prayer obligatory."