* Specific trim level: Different trim packages might have slightly different aerodynamic features.
* Testing methodology: Different testing facilities and methods can yield slightly different results.
* Modifications: Aftermarket additions like roof racks or spoilers will alter the Cd.
While Chrysler/Dodge didn't publicly release a precise Cd for the 2008 Grand Caravan, you'll find various sources online citing values between 0.35 and 0.40. Treat any single number you find as an approximation. It's not likely to be precise to more than one decimal place.