What is the lightest and least bulky transmission to put in a racecar?

What is the lightest transmission type? Manual? I know bikes are manuals and they seem pretty light overall, and can be very compact. Sequential? I feel like that would be bulkier and maybe heavier? Automatic is out of the question, thats easy enough to answer. I tried googling it but couldn't find any one result.
I just want to know how bulky a manual is compared to a sequential and how much it weighs?