Write SQL query to solve given problem: How many authors finished the paper "An Improved Active Suspension Model for Attitude Control of Electric Vehicles" together?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT COUNT(T2.AuthorId) FROM Paper AS T1 INNER JOIN PaperAuthor AS T2 ON T1.Id = T2.PaperId WHERE T1.Title = 'An Improved Active Suspension Model for Attitude Control of Electric Vehicles'