看了以下文章，感觉如果是KEYLESS系统的车，最好检查一下要买的车或现在的车是否
有足够清楚的警告信号。NHSTA 还没定标准，可能2015年才会推出。文章指出现在（
2014 March)没有一款车真正达到NHSTA提议的警告音量。 http://www.safetyresearch.net/blog/articles/nhtsa-opens-smart-k
这三种情况都在文章中有真实例子（包括死伤）。
check following: （检查方法是我自己根据文章内容总结的）
1. prevent incident from engine is running while driver left.
testing audible warning sound inside/outside car, when engine is still
running and driver leaves car while remote is along with driver or while
remote is inside car.
2. prevent roll-away car while engine is turned off but shift is still in 'D'
testing if car can change "D" to "P" automatically when engine is turned off
while car stops with shift in "D".
testing audible warning sound inside/outside car when engine is turned off
while car stops with shift in "D".
3. prevent remote is outside car while driving. (driver might pass bag with
remote out of window to other people)
testing audible warning sound inside car when driving car while remote
outside car.
