The other thing to remember with turbo charged engines is that they usually require a higher octane gasoline.

I think that if I need to tow something, I will use my Grand Cherokee.

 

Maybe 'usually' is correct, but the following may be also:

 

The CR advice is good advice, but the higher compression involved with turbo and super charging almost always results in a requirement for higher octane fuel.

 

AND...if there is an "either/or" option (such as with the Mazda 2.5T), it's because the engine employs a knock sensor which will advance the timing when premium is used which results in increased horsepower. As always, you have to take anything automotive in C/R with a grain of salt!

 

You sound like you are anxious to blow a forced injection engine to save money on gas. I will use whatever fuel is required for a particular engine and, depending on the use of the vehicle, I will possibly use the fuel recommended for a particular engine.

I will say that if you burn up a forced injection engine that calls for 91 octane and they find you have 87 in the tank, your warranty will be void.

 

I just located this from Car and Driver: The new engine is the biggest change, and it's the same turbocharged 2.5-liter four-cylinder found in the Mazda CX-9 three-row crossover and the Mazda 6 mid-size sedan. In the CX-5, it makes 250 horsepower and 310 lb-ft of torque (that's if you use premium fuel; as with those other models, Mazda quotes a lower output of 227 hp on regular gasoline). It'll be available on higher trim levels paired with a six-speed automatic transmission, and we presume it will be available as both front- and all-wheel drive. The base naturally aspirated four-cylinder engine should carry over into 2019 without any changes.

 

That will be a peppy, little machine. I like that they have designed the option for regular or premium into the system. You can then use regular for normal stuff and load a tank of premium if you want to be stupid or need towing capability.

 

That's exactly the point I was trying to make in #24 above. Your response in #25 makes no sense.

 

It makes perfect sense if the system isn't designed to use different grades of fuel. Many are not designed that way and using lower octane fuel in those FI engines can be catastrophic.

 

I commend yo for your choice. I don't drive that much to warrant not purchasing what I want.