Also modern cars produce orders of magnitude less emissions its actually somewhat difficult to kill yourself with one now, you essentially have to run a hose from the tailpipe to the cabin.

You still have an engine that is producing a certain amount of power, and this is associated with a minimum rate of production of CO2. Some of the other interesting emissions are greatly reduced in modern engines, but the CO2 production hasn't fallen that much.

I was just going off what I heard from a EMT to be honest, he said those types of suicides were much more successful early in his career.