On 07/06/2013 05:59 AM, Király wrote:
I will be driving my father-in-law's Hungarian-registerd car around
Hungary and Croatia soon. I have a British Columbia (Canada) driver's
license.

I know that IDPs are "accpeted" in those countries but is the IDP
really needed anymore? If the police stop me will they hassle me if I
don't have one?


An IDP (or IDL) is simply a translation of the driver's license.
Strictly speaking it has no legal value, only your original driver's
license counts.
What might be more important to check, is what third party insurance,
if any, covers you if you drive the vehicle. Vehicle insurance laws vary
from one country to another - in some, the driver is insured, in others,
the vehicle itself is insured for third party liability.