My previous coach (08 Safari Simba) had the C7 ACERT engine and for the most part was a trouble free engine for the 35,000 miles I drove it. It did have one abnormal aspect to it, as it did not like to start immediately. I would have to keep the starter engaged for about 7 or 8 seconds before the engine would run on its own. However, I found that if I plugged in the engine heater a couple of hours prior to starting (regardless of the outside temp), it would start a little quicker...mayby 3 to 4 seconds with the starter motor engaged.
This was never really a problem, just a little annoying. The engine ran fine, had plenty of power and over the 35K miles, I averaged 8.6 mpg (even with pulling our 4000 lb toad).
Ron