Given that one of the advantages of taking transit is that it should save you money over the cost of driving+parking, it probably won't have that much of an effect may discourage people from taking transit and to drive instead.
As it stand with current rates, for trips [HTML_REMOVED] 10km radius from where I live in Vancouver it's cheaper for me to drive and park than to transit in about 75% of all cases. This is for trips from home [HTML_REMOVED]1hr and assuming the price of the ticket and the gas are the comparative incremental costs. (ie: insurance and car ownership costs are sunk costs and not factored in)
Not to mention driving is faster, easier and way more convenient.
If the goal is to make the roads less congested, the system wouldn't be setup to punish 'short-haul trips' (which I believe make up the majority of car trips in cities).
Then again, if short haul trips through transit were encouraged through by lowering pricing, the GVRD would lose a LOT of the transit tax revenue from fuel sales at the pump. In that sense there's a bit of a cognitive disconnect going on when it comes to pricing transit to be more accessible than car trips.