This is an issue not unique to Logstash but applies to most command lines...its a simple mistake but should make complete sense when I point it out, lol.
Each command you issue can be followed by an argument/option. Typically, a space is used to separate these two, just like you did with Logstash -f. So what happens when your path has a space in it? The command line thinks your issuing an additional argument or command. Look at your path, locate the space and you'll see that the error matches up with it perfectly.
The fix is straight-forward, encase the path in double quotes logstash -f "C:\Downloads\ELK Stack\logstash-6.2.2\data\logstash-cars.config"