I did a similar thing don't worry! I had to do a thing where I would just take 1 angle of each car, which meant I only had to walk down every other row, and only divert when something special caught my eye! This was especially helpful when I got out of the pre-93 section. Even with that, I was just walking past Aston Martin V8s like they were nothing, there was just so many!
I walked down the middle of the two rows of the cars that were parked up against eachother, rather than the big gaps that were left for the cars to drive out in. That way, I could do two rows of cars at once!