Jesus died for that sin as well as any other I may commit. I will go immediately to heaven (assuming the car has killed me).
b) You are a great Christian, but you are angry with someone, and you set fire to their dog, and then you are run over by a car.
Well, I would never do this, but for purposes of argument - again, Jesus died for this sin as well as any others I may commit. I would go immediately to heaven.
c) You are a great Christian, but you are angry with someone, and you murder them, and then, you know, splat.
Same as the answer to b.
In each case - what happens? Are the results in each case all exactly the same?
Yes, because the blood of Jesus is sufficient. He said, "It is finished" or "tetelestai" (meaning the debt is paid - I believe that's spelled correctly). At any rate, I know I could not save myself by doing "stuff" to begin with, so why would I think I can keep myself saved by doing "stuff"?
As Christians we do "stuff", but it is because of the Holy Spirit within us, not because we are trying to do something now that we never had the power to do in the first place.
So ... I could commit murder an hour before my death, and die impenitent, even cursing God and that's OK. I'm going to heaven. Because Christ died for my sins.
Why then trouble to follow a single commandment? After all, 'Christ died for my sins'. I can be the most heinous serial killer, and spit in the eye of the Priest at my execution. Its all good, because - hey - 'Christ died for my sins'.
I hope, thus baldly stated, that this kind of 'faith' can be seen to be as crazy and as hellish as that of any death cultist.
We must repent of our sins, and also stop doing them. Christ saves us and frees us of our sins, and is always ready to forgive us. But we must will it, we must cooperate with our salvation. It doesn't happen despite ourselves.
Hope this was helpful.