Congratulations on your new car.
You may want to check and see when it last had its transmission service. It might need one.
Additionally be sure and simply check the ATF level when the fluid is warm (typically after about ten minutes of driving). The level should be between the two marks.
Enjoy your drive,
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)