PT GT Reg gas

I haven't, but I've heard that people who do, run the risk of engine knock that the knock sensor can't handle, possibly causing damage. The performance will definitely suffer. At least I would use mid-grade, 89 octane. It's probably not going to be worth the money you save.

SRG

On my daughers twin cam 1998 Neon regular pings excessively - Midrange does not ping audibly. Running mid-range gives better mileage - she has not tried Premium yet - would L:IKELY not imprve mileage enough to pay for the "premium" price.

yeah except the GT requires premium...

The manual says they recommend but do not require 91 octane(not premium 93 octane) but a good 87 octane is ok

kinda defeats the purpose of owning a turbo charged car, if your running low octane fuel the pcm compensates, and you will get lower hp.

Octane demands vary with outside temperature, humidity, altitude above sea level, motor temperature, and the load on the motor. There are even motor to motor differences. In the winter, when not pulling a load or driving in the Alps, 87 might be adequate.

Richard.

I own a PT GT, no 87 won't be adequate, no matter the temp, humidity, or if a cow jumps over the moon. You will get knocking, and lots of it. Not much else