Simplified SqlReader operations

var customers = new Dictionary<string, Customer>();

While(sqlReader.Read())
{
    // If you give the Customer object public properties you can initialize
    / like this.  The class also requires an empty constructor.  This is default if you don't add a constructor
    Customer customer = new Customer()
    {
        FirstName = sqlReader["FirstName"]?.ToString() ?? "",
        LastName = sqlReader["LastName"]?.ToString() ?? "",
        Vin = sqlReader["Vin"]?.ToString() ?? "",
    };

    customers.Add(customer.Vin.Trim().ToLower(), customer);
}

// Customer Class example  (you may already know this)
public class Customer
{
    public string FirstName {get;set;}
    public string LastName {get;set;}
    public string Vin {get;set;}
}