Another thing most press accounts are getting wrong is that she wasn't trying to ram her way into the White House. She drove up to a security check point, probably accidentally, and when confronted by the security personnel, flipped out and rammed her way back out.
From the Washington Post:
*At the beginning of it all, Oregon residents B.J. and Susan Campbell saw a black sedan driven by a woman heading west on Pennsylvania, into a security checkpoint at 15th Street and Pennsylvania Avenue NW. The driver went about 20 yards, B.J. Campbell said, before rapidly turning the car around at the concrete security barriers.
“The Secret Service guy was just having a cow,” B.J. Campbell said. “Yelling at her and banging on the car.” The Secret Service officers pulled a black metal gate into her path and she slowed to try to go around it. Then the agent moved the gate in front of her again.
At that point “she just gunned it,” B.J. Campbell said. “She ran the barricade down and the guy; knocked him up onto her hood. He rolled off into the street, and she tore off down Pennsylvania Avenue.” The whole encounter lasted about 20 seconds, he said.*