A 4:57 is equal to about 16:50 for 5,000 but unless you are over 40 who cares! If the desire is to make yourself feel better by winning a very weak local roadrace with zero competition then go for it and put in all those crap miles and feel zoned-out stoned all day long. Be a track man and read up on Dave Wottle, Billy Mills, Bob Schul,et.al.
Leave Alberto to the tye dye crowd and get tough a.k.a. Marty Liquori.
Be an athlete, do lung-searing workouts and drop that 1600 time down to the 4:30 range....or you can go out and plod like all those other fools and "run" a marathon in 4:15 (ever walk fast for one hour?) The point is, you need speed.