How toFocus a Keyword and target the right traffic!

Hello everybody (this is an example only)
Say for example my keyword is
'average miles per gallon' 10000 for [exact] search, 10000 for "phrase" ,50000 for broad and my website is averagemilespergallon.com

say for example of those 10000 people there is people tha types that keyword or phrase also for this reasons :

1) 'how can i increase my average miles per gallon'

2) 'average miles per gallon with a full load on my Chevy track'

3)' tips to increase average miles per gallon'
4)'average miles per gallon for a old chevy'

5)'average miles per gallon for a old Chris Craft boat'

6)'average miles per gallon for a ignition engine'
7)'average miles per gallon of a Ferrari'
8)average miles per gallon at 100 degrees
9)my average miles per gallon are very low when outside is 30 degrees.

and so on

in those 10000 people There is also people as you see in my examples merely interested in statistics and not all are interested in the -tips how to increase miles per gallon- so if i create a blog to properly promote my book "10thousand tips how to increase the average miles per gallon in your car" my keyword should be more focused! am I correct? more focused in the product I'm going to promote more targeted to the people interested to tips how increase the average miles per gallon than not generally interested to those keywords!Am I missing something ?My keyword "average miles for gallon" is TOO generic or it is correct? My keyword should have been "average miles per gallon tips to increase them"(is to long is only an example) am i wrong I hope i have been clear in my concept.Thanks everybody.Its like a bullet that explodes in thousand of particles,few of them may reach my target and many of them are simple wasted in different directions.Is not the entire bullet sent directly to the target.
What do you think?