I have ACC on my new Mazda 3 and it is a great option for those who frequently drive highways and are used to using cruise control in the past. The technology has evolved so that the whole "Control" is much smoother.

Last weekend, I tried this out on a derestricted stretch of freeway and set cruise at 140km/h (87mph) and the 2/4 distance setting. As I approached a vehicle doing 120km/h (74mph), I deliberately stayed in my lane. The vehicle let off the throttle, then gently braked down to match the vehicle's speed. After a little while, I changed left and the Mazda accelerated (smoothly) back up to 140km/h. I even tried this in an urban area, obviously at a slower speed setting, and it worked great. As good as a human driver. Makes long-distance driving quite easy. With the more advanced systems on the BMW, the Stop & Go will bring the vehicle to a standstill if you approach stopped traffic.

That said, if you don't do a lot of highway driving and/or don't use cruise control normally, the benefits are more muted.

__________________
2014 Mazda 3 GT: Ø Consumption: (click for details)