我倾向于认为轿车司机要付全部相关刑事责任和部分民事责任。
首先，大家都在问要不要负全责。这个“全责”是中国交通法的概念，新加坡没有这个概念。请不要用中国的法律概念套用新加坡法律。
第二，刑事上，新加坡法律规定不管别人有没有错。你有错也是你的错，和别人有没有错无关。
Charlesworth & Percy on Negligence (Sweet & Maxwell, 10th Ed, 2001)上这样说：
para 9-186: [T]he duty of a person who either drives or rides a vehicle on the highway is to use reasonable care to avoid causing damage to persons, vehicles or property of any kind on or adjoining the highway. In this connection, reasonable care means the care which an ordinarily skilful driver or rider would have exercised, under all the circumstances, and connotes an 'avoidance of excessive speed, keeping a good look-out, observing traffic rules and signals and so on.'
para 9-219: It is the duty of the driver or rider of a vehicle to keep a good look out. Indeed, a driver will be held negligent if he fails to notice in time that the actions of another person have created a potential danger. He must look out for other traffic, which is or may be expected to be on the road, whether in front of him, behind him or alongside him, especially at crossroads, junctions and bends.
Public Prosecutor v Lee Cheow Loong Charles [2008] 4 SLR(R) 961是一个很典型的例子。行人闯红灯横穿马路，司机未注意，撞死了。法庭认为司机明知是灯控路口，但未尽注意观察义务，所以需要为撞死负责。
所以轿车司机被控基本上是跑不了的，要么是刑法304A条，要么是交通法64条，要么是交通法65条。不打方向灯不查盲点，刑法上不会对你怜悯的。
3. 民事方面，司机有可能付部分责任。
这里就会有摩托车疏忽的部分的影响。司机撞死人肯定是疏忽的。因为摩托自己责任的原因，最后赔偿应该不是100%而是一个百分比，具体要看法庭的意见，我不知道答案。