I have a 2012 Subaru impreza, manual transmission. Most of the time it works great, starting with no trouble. However, from time to time it will have trouble starting. At those times, if I either a) keep cranking for 5-7 seconds, or b) stop cranking and wait 5-7 seconds before trying again, it will eventually start - I've never had it not start.
This does not appear to be temperature dependent - I've had the issue both in the middle of summer and the middle of winter. It does seem to happen most often when parked on a slope, however I haven't noticed if being sloped forward or back makes a difference. And of course it's too intermittent to be able to take it to a shop and say "see, it has problems!"
What are some possibilities of what could be causing a problem like this?