Although I'm not 100% sure since I don't work there, the most likely explanation is using gelatin to keep all the 'solids' in place. It's a common food photography trick. :)
While I understand the reasoning, it's not advised to drive with one hand on the stick áll the time. Only when actually shifting. Even more so, it's not necessary all the time either. On a highway you have to shift to the highest gear, keep both hands on the wheel and both eyes on the road.
Where I'm from, driving stick is taught as a standard. If drivers don't show to be sensible in the way that you simple "can't" do anything else with your hands but driving when driving, they shouldn't be in the first place. This goes for all ages.
My best guess is either gelatine or flash frozen with liquid nitrogen. Keep in mind, it might've been accomplished very differently altogether.
Even more so, it's not necessary all the time either. On a highway you have to shift to the highest gear, keep both hands on the wheel and both eyes on the road.
Where I'm from, driving stick is taught as a standard.
If drivers don't show to be sensible in the way that you simple "can't" do anything else with your hands but driving when driving, they shouldn't be in the first place. This goes for all ages.