Cheap gas is defined as gasoline which only has the minimal EPA level of additives. Gasoline that has the minimal amount of additives is not good enough for the Intrigue if you want peak performance.The Northstar engine is a very high performance engine. There is no way in knowing how much additive you are getting in your gasoline unless it is a Tier-One gas. Tier-one gas is more than a marketing tool for the gasoline companies since the major car manufacturers (except Ford) pushed for more addtives. The fact that not all gasoline marketers have joined the tier-one program doesn't mean anything except that they know that the vast majority of Americans are ignorant about cars and gasoline.
I know that the additives work because I have driven cars using minimal additives for thousands of miles and then gone on a long run trip where I use Chevron gas. After about 5 tanks full I noticed a distinct improvement in performance. BTW, the Shell gas I ususally buy for a penny more a gallon as opposed to "cheap gas" is actually cheaper for me to buy since Shell gives me a 5% rebate, which at $3 a gallon is 15 cents. Hence, the tier-one gas is 14 cents cheaper. The best of both worlds.