Is using a car مكروه (reprehensible/discouraged)?

What your colleague said is incorrect. Using a car or any other means of transportation is permissible as long as there is no external impediment. The Prophet, peace and blessings be upon him, and his Companions used the available means of transport in their era, and Allah has blessed His servants with them. The default rule for things is permissibility. As for riding to the Friday prayer or congregational prayer, walking is better for those who do not find it difficult. This does not mean that riding a car is disliked; rather, it is contrary to what is superior, as walking to the mosque carries a great reward.