Only if you have the vehicle booked continuously for your entire outing.
Details:
If your reservation is continuous (for example, 6:00 PM to 12:00 AM) and the driver stays with the vehicle the whole time, then yes, you can safely leave your belongings inside.
For split trips (e.g. pickup at 8:30 PM and return at 11:30 PM), belongings cannot be left in the vehicle.
The driver may have another trip in between.
Return trips often use a different driver and a different vehicle of the same type you booked.
We cannot transfer items between vehicles or guarantee secure storage.
Bottom Line:
If your booking is not continuous, please take all belongings with you when you exit the vehicle.