When it comes to vehicle expenses make sure and claim them!! It makes a huge difference. For myself I keep track of all km's I drive for every trip I make for groceries, supplies, etc! anything. I give my accountant my totals of km's driven for each category (50% for groceries, 100% for all supplies etc). He then claims a portion of my gas, portion of my car insurance/driver's licence and a portion of my car repairs. I think it was almost 9000 in deductions I claimed.
when it comes to logging km's I don't actually keep track of what I drove. On my spreadsheet that I use to keep track of my daycare expenses I have a column for km's. So for a trip to walmart I use 8km, for superstore I use 16 etc. then they all get totalled at the end. I don't actually worry about tracking actual km's in my vehicle. Does that make sense? I do keep gas receipts during the year, not sure it would matter though.