Credit Card usage is necessary to build a strong credit score.  While it is possible to have a credit score generated without the ownership of a single credit card, it is unlikely that an individual would be positioned to build or maintain a high credit score.  The credit scoring model prefers revolving usage of credit.  A credit card provides the best vehicle for revolving credit terms. 
An installment loan such as an auto or other loan type with fixed terms have pre-arranged the number of months financed for a purchase, and a fixed monthly payment.  Typically the interest rate is fixed, but could be variable such as an adjustable rate mortgage (A.R.M.).  Credit scoring does not factor in the rate of interest or the type loan (Fixed or A.R.M.). The type of account(s) makes up approximately 10% of a credit score.   What's important to understand is that credit scores do not factor in your interest rates, the terms of your accounts or your income.  When credit cards are used the balance and monthly payments constantly change.  The credit scoring models predict that your most recent history is the most revelant.  A car loan that has a four year payment term that you started two years ago will show your payment history.  Credit scoring recognizes that your purchase was based on a decision from two years ago and that your current payments are required maintenance.  Credit cards are believed to show your current financial strength, as you have the ability to frequently change the balance and required payments.  This is why accounts that are revolving in nature are more preferred by credit scoring models.