Geometry of nose in and nose out parking in parking lots
Sorry to disappoint despite the (now removed) eponymous tag :-), but in fact I don't have a precise answer. Here are three possible sources, the second two mathematical.
(1) "You're Parking Wrong: Why it's almost always better to back into a space than pull into it head-on." Tom Vanderbilt, Slate, Feb. 2011. (Article link.)
(2) "Mathematical Analysis of the Parallel Parking Problem," William A. Allen, Mathematics Magazine, Vol. 34, No. 2 (Nov.-Dec., 1960), pp. 63-66. (JSTOR link.)
(3) "The Geometry of Perfect Parking," Simon R. Blackburn, 2009. (Web link leading to PDF link.)
The two math papers concentrate on parallel parking, which is not your question,
but is nevertheless quite interesting.
Here is a nice figure from Allen's paper: