I tried one of the Cooling System Technologies 5504 locking fuel caps from Autozone. This is going to sound insane, but I swear my HHR felt like it was just a little bit sluggish after putting this cap on. So today I put the factory fuel cap back on and the perceived sluggishness is gone. No CEL was illuminated on the dash by the 5504. But I have to wonder if it didn't jibe just right with the evaporative emissions system or something.

 

Welcome to another Orange HHR Owner

 

I went to the owners manual, 2006 version, I could find no reference to a No CEL indicator light, please , more detail

 

Check Engine Light.
He's saying that he didn't get an error, but thought there might have been a problem anyhow, because the engine seemed less responsive.

 

Exacta-mundo

 

Couldn`t figure that one out...
But a CEL pretty much only comes on when the engine isn`t running, and some one had previously said (not this thread) there was a low power read-out on the DIC, that`s why I went to the manual to get clarification.
And it was 6:15am, still drinking wake-up juice...Sorry Guys.

 

That is the one I use (Wal-Mart version) and I saw absolutely no difference in the car. It does sound insane. But YMMV.