this for loop inside arrays is working like while and printing only the second index.
what should i do to make it print only even indexes?

this for loop inside arrays is working like while and printing only the second index.
what should i do to make it print only even indexes?

You have inverted the += operator in your for loop. You're saying i = +2 which is the same as i = 2
The correct code would be:
for (int i = 0; i < cars.Length; i += 2)
{
Console.WriteLine(cars[i]);
}