This thread is full of bad information and advice.

1. At DCA, OP's daughter will walk past at least three banks of kiosks between her airport curbside or the garage. It will take her between 30 and 45 seconds to obtain either a BP or a security document which gets her to the gate.

2. OP's daughter's chances for Pre-Check won't be affected by whether she checks on online, at a kiosk, at the counter or at curbside at bag drop.

3. GE entitles OP's daughter to be considered for pre-check. While most GE holders who properly enter their KTN in their PNR / Profile and who have taken care to have their ticketed and GE names match exactly will be selected for pre-check 100% of the time or close to it, there is a remote possibility that one is selected for pre-check and then randomly sent to standard screening. I recently asked an Officer how it's handled at IAD which has a separate checkpoint for pre-check. He told me that he hadn't seen a random denial after selection in over 6 months.

So, bottom line is that OP's daughter faces a delay of 30-45 seconds and no impact on pre-check. Purchasing a preferred but not MCE seat is a waste as she'll likely be assigned to one of those at the gate if there's nothing in the back.