I know that people aren't too keen on buying cars from dealers and showrooms but I found showrooms and dealers easier to navigate when compared to pakwheels and olx. Here's my story:
I moved from Karachi (sold my alto 2006 vxr there) and came to Islamabad, had to join my office within a week (so had only a week to get a new car). First, of course, I started looking for one online... cold calling, arranging meet-ups to see the car (most of the cars were completely different from how they looked in pictures of course which is fair)...the point is, that I was able to check only 3-4 cars per day, and this was while driving around RWP and ISB for the whole day.
My family was going to arrive within a week as well so I knew that I only had this one week (3 days gone already). So, I resorted to showrooms and dealers. To my surprise, the prices were the same and there was sooooo much variety in quality and products - so much more choice when compared to websites. During those 4 days, I guess I checked out over 50 cars, test-drove at least half of them...and made a well informed purchase at the end (at least I think I did).
Showrooms and dealers - even though are very shifty - give you A LOT of options FAST! You learn quick!
I think the most important thing, before embarking on the car-buying journey, is to spend time in finding somebody who knows about cars and one who you can trust. I had that somebody with me this entire time since I didn't know much about car-buying at the time. If YOU are that person yourself, then I believe going to the dealers and showrooms to buy cars is still the best (most time efficient and thorough) method of car buying.