I went to the F1 race last year, and I wouldn’t consider taking any other means of transportation to the track other than a taxi, rideshare, or rent your own car. The lines for buses, and even the taxi line, (you have to line up your taxi ahead) were very very long. I found a rideshare last year just by going on fb and going to the sepang page and made a post. A young Malay guy and his buddy took me, my brother, and a german guy that they knew to the track on Saturday. On Sunday, my brother and I took a taxi straight from the hotel to the track and had the guy pick us up after at a specific spot. We spent probably 120usd total for the taxi, but it was well worth it. If you can get like 4 people to chip in on it, it wouldn’t be too bad.
For every one story I have heard of that working out well, I have heard three nightmare stories involving anything with public transportation. I have only been once myself, so I am by no means a expert.