Print distinct car names with count in descending order
I'm sure that someone who knows more Python than me will be able to provide more feedback, but I see a couple of issues.

The first is that the core of this functionality is implemented by collections.Counter. We can just write this:

def frequency(lst):
    counter = Counter(lst)
    return reversed(sorted(counter.items(), key=lambda x:x[1]))


The second issue is with these lines:

item_list = [item.lower() for item in item_list]
item_list = [item.strip() for item in item_list]


We can just write

item_list = [item.lower().strip() for item in item_list]


Or as @janos suggested,

item_list = [item.lower().strip() for item in data.splitlines()]