In game score

I was entering the scores for the Hyper car contest, and I noticed that the number of competitors was changing, between 1 and 4 all for the same year, is there a way to get all of the cars I have in the competition to be competitors and have this number consistent?

That stat is irrelevant. What is happening is the following: the game checks how many cars are within the top 25% of competitiveness in that demographic. So if you have a car with 130 competitiveness it would automatically show “1” because you are the only in the top 25%. It gives an estimate for how contested a market space is.