RANK - Non unique values by subset.

Hello,
I need to rank the values of a specific column, but based on subsets of drivers as shown below. Also, I want to rank unique values so that when 2 values tie with the same rank, the next value only increments by 1 and not 2. Data may not be in any particular order.

Driver Miles Rank
Matt 20 2
Matt 50 3
Bob 50 2
Matt 10 1
Matt 10 1
Bob 25 1


If you were to sort this...
Matt 10 1
Matt 10 1
Matt 20 2
Matt 50 3

Bob 25 1
Bob 50 2

The following formula works great for ranking the entire data set, but I need to somehow incorporate it to look at subsets (drivers) when ranking
=SUM(--ISNUMBER(MATCH(ROW(INDIRECT("1:"&RANK(DataTable[@Miles],DataTable[Miles],1))),RANK(DataTable[Miles],DataTable[Miles]),0)))

Any help is greatly appreciated!

Thanks Tony! This looks like it's working.