Check your owner's manual. 

Posted by: @frs

I currently fill with 7.5 gallon of 93 and the rest with 87, this gives an average of 91. lol

Are ya sure? If you mix whiskey with methyl alcohol, you'll still go blind.

I think this is proof your car will run fine on 87.

The publication ‘Car and Driver’ indicates in it’s listing of specs for the 2014 Scion that premium fuel is required. 
The website: http://www.fueleconomy.gov also indicates that premium fuel is required for this vehicle. (those are the only two sources that I checked.) 

Mixing 7.5 gallons of 93 octane gasoline with 5.5 gallons of 87 octane in your 13.2 gallon capacity fuel tank actually yields 90.46 octane, LOL. (accounting for the 0.2 gallons which would  be remaining in the fuel tank if you are able to drive it to the gas pump)  But I am not sure if that is how mixing octanes can be calculated or measured.

I do not know the long term deleterious effects of using a lower octane in your vehicle.     But if 93 is available and premium fuel is required, then the higher cost you pay now may be much lower than the cost of engine, etc. repair later. 

Looking up the owner's manual myself, it requires at least midgrade gas. Just use midgrade. You picked the wrong car if you're wanting to skimp on gas. Around me, the difference in price for 10 gallons of gas is only $4.00. It's not even the price of two 20 oz bottles of soda.

waste of money

https://www.youtube.com/watch?v=dmNQ66AtyWk

https://www.youtube.com/watch?v=PD6y2PtIu8Y

Ive watched a ton of Scotty's videos.  I was just hoping to get a response from him.  I know what the manuals say,  I just value what Scotty has to say.