This part must be printed in a vertical (standing) orientation. Printing flat would align layer lines with thin “grips” on the model, significantly weakening them and increasing the likelihood of breakage.

Material: 

• PLA is likely to melt in a warm car unless the vehicle is only driven in Siberian. 
• PETG may work, however I've had other models deform when printed in black PETG-HF that were exposed direct sunlight while in a vehicle.
• It may be necessary to use a more heat resistant material such as nylon or ASA.