I had a 2012 Cadillac CTS Coupe Performance (sold with 65k miles) and now a 2014 Cadillac CTS Coupe Premium (currently with 38k miles). Same V6 engine but the 2014 getting 15-16mpg, compared to the 2012 with average 17-18. (combined mileage) Any thoughts? Thx!

It should be about the same. They both had LFX engines. It might be that emissions regs inched up a little in that time, but that'* speculation on my part, and a bit of a stretch if I'm honest.

Are you driving about the same routes and with the same style?

Are your MPG readings from filling the tank and doing the math or from the computer'* opinion?

Possible...bit less 'driving' and more 'idling'?!? Thx for your thoughts!

Ah yes, that adds up. The PCM has got to keep those catalytic converters hot when idling.