In 2010 the CRA reduced the requirements surrounding the logging of business use of vehicles. Previously users were required to log 100% of their trips. If you want to know more about this, check out MOTOR VEHICLE RECORDS.  As a result of all the work required to maintain the log many were not adhering to the requirement.The CRA recognized this and made the following adjustments:
Log book must be kept for 1 year to establish a baseline business use percentage.
After the initial baseline line year, taxpayers are only required to log 3 months of the year. That amount can then be extrapolated out for the year. 3 months records are still required to ensure that the baseline is still reasonable.
To measure if the baseline is still reasonable a 10% deviation is allowed.
The 3 months logged each year also has to be representative of the vehicles usage for the year.It's not often we get such good news from the CRA, so this is pleasantly surprising and welcomed. For more info, visit MOTOR VEHICLE RECORDS. _