My take:
PeaceblinkfriendSuppose I found this to be the case some time ago and I still find this to hold true
Depends on your emphasis. I would use the present tense unless I was referring to a particular incident in the past.
I find/found it difficult to park a/the car along a/the kerb.
a car? Only if you want to be general. Not very natural in most cases, unless you are a DOT officer analyzing how parking friendly the street is. The car is OK. doesn't sound like your car. It makes me think you had difficulty parking a rental car or someone else's car which you're not used to either because of the size or manuverabitly of it.
Or just "PARK along ..." It's understood.
The curb - specific curb.
A curb - any curb. very general just like the explanation for a car.
My explanation may not be correct though I'm quite confident it is :) . Just my opinion.