Short answer is Yes you can.
However let me explain a bit.
Cars can cross Shandur and they do cross Shandur but with chances of failure, We too saw two cars crossing Shandur. One was an old corolla carrying locals and you will be surprised to know that other one was some small japani car. I guess it was may be Dihatsue Mira or Suzuki Alto. Actually they already have crossed Shandur and now descending to Ghizer when we crossed. We stopped and exchanged some hello hi. They were 4 guys on board and were from Lahore. Later when I was passing through Shandur, Laspur, Herchin, Mastuj Booni etc then all the time I was wondering how did those car guys manage to pass such a rough and tough route without any failure. Seems miracle to me.
So cars can somehow manage to cross Shandur but with great patience and attention. There are uncountable spots where you can easily break something under your car if you lose patience. High ground clearance is a must. Among cars, I have seen Corollas and Mehran the most successful on such rough routes. Once I saw a picture of Suzuki Mehran in Taobut Bala (last village of upper Neelum valley) and I couldn't believe my eyes though I myself have done some adventures on my Suzuki Khyber.
Acha khair, most important thing, if you just want to attend the festival and whole round trip is not the intention then its really easy from Ghizer side. You will find paved road till Phander, even till 10, 12 more kilometers ahead of Phander so offroading would be very less as compared to reaching Shandur from Chitral side. Also ascend would be quite easier, no sharp turns and no steep climbing. You would not be facing some real challenge from Ghizer side.
On the other hand if you want to cross it on car from Chitral side, rehne hi dain mere bhai.
Shandur ki bari bad mai aay gi, first you will regret crossing lowari top if lowari tunnel would not be open that time. Secondly, paved road ends at Booni, and from Booni to Shandur top its more than 80 kilometers which can be a serious test of nerves and patience for driver and reliability for car. And also it will take a whole day from dawn to dusk for a car. Also from Chitral side ascend is quite sudden and steep though it can be done somehow without 4x4.
After this whole story, if you are adventurous kind of person and love to take pangas, says welcome to hurdles and stick with your plans without regret, then go from any side, you will enjoy even if you will break your car halfway. People regret after taking their cars to Kaghan jesi fine road when they have to cross a couple of streams and on the other hand there are such kind of people who cross Shandur and deosai on cars, break bumpers or silencer or some other failure but still enjoy every bit of it.
