That study was not intended to look at how much time an emergent trip to the hospital saved, but (and actually more importantly, though in this setting not neccasarily applicable) if the patient fared better. Not suprisingly, there wasn't a lot of difference between the 2 groups. Of course, the average time saved, since this was based in several urban/suburban systems was not all that much either.
What almost every study that has been done shows, and continuies to show, is that emergent driving WILL save time, though with shorter distances not neccasarily a signifigant enough amount that will affect patient outcomes. How this affects those than actually can shave off 10+ minutes is debatable and as far as I know hasn't been looked at. It's also debatable if an emergent responce when the patient needs an intervention unavailable in the field makes a difference; one study does seem to indicate that it matters.
Bottom line: short trips...speed is less important than avoiding traffic, not having to come to full stops, and using a system like the opticom...long (quite long) trips...an increase in average speed and all of the above will save time, and perhaps a signififgant amount.
http://www.sciencedirect.com/science/article/pii/S0735675711000453 The study indicated in the above post.
http://www.sciencedirect.com/science/article/pii/S0196064495702679 Time is saved, but again, in an urban system where it isn't much, not worth it.
http://informahealthcare.com/doi/abs/10.1080/10903129908958920 Basically same as above, but slightly more time saved.
http://www.emsphysician1.com/media/files/emsp11.pdf Ditto, but does indicate that time saving IS important for interventions only found in-hospital.
