Penske Automotive hits one-week low on first-quarter miss

** Shares of Penske Automotive Group PAG fall 3.7% to $151.835, their lowest level in a week

** PAG clocks its worst intraday pct. drop since April 3

** Auto dealer postsQ1 adjusted net income of $226.3 million, below analysts' estimate of $238.6 million; revenue of $7.60 billion also falls short

** Stock largely flat this year, including the day's move