Yup, agreed, & I'm old here.....

 

Since options can be had across the board (we have LS's at work with the stainless tip from the factory). If it had the 17" wheels from the factory, it's a 2.4. Check the label in the door opening for the tire pressure and that will show the stock wheel size.

A 1LT could be optioned with everything but the 17" wheels or the LE5 suspension, which you can't identify by just looking.

The dealer should be able to give you a full description off the VIN.

 

Our 1LT Panel was purchased new in 2008 with 17" 2LT Silver Wheels (not polished) on it..... Pretty sure they were factory installed .....

 

You can look under the driver's side hood. The Federal Emissions sticker plainly indicates the engine size...2.4 OR 2.2 LTR.

Now strictly speaking of the HHR.....

You can look in the glove box for an accessory sticker. On the sticker look for one of the engine "codes" below.......

2.4 ltr.

LE5 = 2006-2008 years
LE9 = 2009-2011 years

2.2 ltr.

L61 = 2006-2008 years
LE8 = 2009-2011 years

There is also a couple of other engine codes, but I omitted those because they probably do not apply.

These are the only 2 sure (easy) ways of numerically determining the engine......unless the hood has been replaced or the glove box sticker has been removed/door replaced. And since your car is a 2011 it will have EITHER the LE8 OR LE9 code

Edit....Oh, and you can determine engine by VIN (if you can find the correct VIN decoder