Your answer should explain all the parts of this riddle.
The answer (as implied by the second tag) is a single short English word.
Edit: Based on the comment from the question poser:
You are within a league of the finish line.
I could possibly see the solution being:
In rugby, a "try" is worth 5 points.
Let's go ahead and make two of them now 5 5
And then interpret this as a Roman Numeral 6
Then we see
A league is equal to 5556m.
old answer left for posterity
The number of days in a leap year.
a homonym of the prefix "tri-", which indicates 3.
a homonym of "two" and then "tri-" again, which indicates 6.
interpreted as Roman numerals, we get 6.
Composing this gives us
366: the number of days in a leap year (such as 2016).
It's not yet clear to me if the title is related.
Three (as in tri)
6 (VI is 6 in Roman Numerals)
So Vivienne really likes
Mazdas? Specifically the Mazda 323 and Mazda 6
Perhaps this is an
Vi (or vim)
will result in an
BMW model# 525 or 526
How did I get there?
= 5. a try in rugby is worth 5 points
The second (TO), fifth (TRY), fifth (TRY) and sixth (Vi) letters of the alphabet.
TRY = 5 because a try scores 5 points in rugby. Based off my first answer
I believe the word is
Plan / Scheme
Try to Try
If we read this as "Try to Try", we get to something extremely different than if we were to pause after the first try. Essentially, this hints that the narrator is telling someone to try, however, not to do x. He's telling someone to try to even attempt at doing x. Incentivating/Motivating of sorts. Before trying to do something, a plan(Trying to Try) must be formed, and only then it's executed (the 2nd try).
I'm somewhat inclined to believe that this is misderection and just a calling. Usually on letters the receipient is identified by ",receipientName", and as Vi can be short for Vivienne, that's my reasoning.