Interesting question. I was curious about this myself. In the Ford, the company claims 240 HP @ 5500 RPM, 270 lb/ft of torque @ 3000 RPM, and a 9.3:1 compression ratio. The Evoque claims 240 HP @ 5500 RPM, 251 HP @ 1750 RPM, and a compression ratio of 10:1. According to the article on Wikipedia ( Ford EcoBoost engine - Wikipedia, the free encyclopedia ) the engines are the same. Typically, below about 11 or 12:1 compression ratio, you could use regular gas with no ill effects. Above that, usually premium is recommended. Modern engine monitoring systems like pink or knock sensors will retard timing to stave off ping (technically called predetonation, which is the fuel/air mixture igniting before the spark plug fires due to compression as the piston is compressing the mixture). Most likely, the engine won't be damaged by running some regular gas; whether it really needs premium all the time is debatable. Modern engines use computer mapping to define the 'characteristic' of the engine; in all likelihood the Evoque 'feels' much different to drive than the Edge. I've driven both, and I think there is a difference in feel. Here's the problem: if the engine is mapped to give maximum acceleration and max power by tweaking the timing, it is possible that even a low compression engine will require premium gas. It all depends on how the factory mapped the engine module.
You will hear all sorts of stories about octane. My wife had a VW Tiguan that 'recommends' premium gas; she almost always put regular in it and it ran fine up to 72K miles when a lady hit her and totaled the car. My Mercedes "requires" premium gas (GLK 350 with 3.5L V6); and I almost always use regular, once in a while I will put premium in it. I do not notice any difference in performance or gas mileage switching between the two. I have 81K miles on the Mercedes with no ill effects.
My best advice would be to try both premium and regular, check your mileage and turn down that glorious 17 speaker stereo and really listen to your engine. If you hear even the slightest hint of pinging, try higher octane gas. If you don't and it feels fine and runs well, stick with it. And drive that thing!
With all of the computer fuel management and other electrickery I doubt that you will see a whole lot of difference in fuel economy or performance if using regular 87 octane or 89 octane fuel. But there will be some benefit to using the higher octane just not in big noticeable amounts. I use 93 octane 100% gas (no ethanol) when I can get it and my normal fuel economy is 24 mpg. I am on the pedal and use Sport mode for everything but highway driving. I hoon it up as much as I want. I have gotten 27 mpg on a long highway drive with mixed 93 octane fuel. What do you get? Ford is advertising 30 mpg but what are the real world numbers?