move 13 by red is good. I believe red should move car 2=4..then black's 8 pao and car look funny..cannot 'feng' anything at all.

move 15 i think should move car 6+5. Black's opening weakness is his both horses.

coz normally black move pao 8+4 or pao 2+4 to feng car and whack bing ..to prevent red bing 5+1. this time round...red realises black wishes by bing 5+1.

i suggest move car 6+5, then later car 6+7....same thing for car 2=4, car 2+5 to pin down two of his horse.
anything..use central pao to whack center bing.