[Perian]

Taking a good look at the 2009 GM Product Guide shows some MPG improvements gained in various ways.

Some examples are shown below.

Saab 9-3 Aero:
2008 MPG: 16/26
2009 MPG: 19/29
How it was done:
Aero-type appearance and performance package is now an available option on 2.0T 4 cylinder “Sport” FWD models.

Chevy Aveo:
2008 MPG: 24/34
2009 MPG: 27/34
How it was done:
Powering the Aveo lineup is an enhanced version of GM’s sophisticated 16-valve DOHC four-cylinder engine. Technologies such as electronic throttle control and an electrically controlled thermostat to help maximize performance and efficiency across the rpm range. It also features an integrated oil cooler with piston spray nozzles.

Chevy Colorado:
2008 MPG: 18/24
2009 MPG: 18/25
How it was done:
Added a fuel system control module for improved fuel economy – up to 25 mpg on the highway with the 2.9L engine.

Chevy Cobalt:
2008 MPG: 24/33
2009 MPG: 25/36
How it was done:
More efficient and more powerful 2.2L Ecotec with variable valve timing, new 3.63 final drive ratio with the manual transmission and new 15-inch low-rolling resistance tires.

Chevy Malibu LT/LTZ:
2008 MPG: 22/30
2009 MPG: 22/33
How it was done:
Introduced late in the ’08 model year on LTZ models and expanded to LT models in 2009, the Malibu’s 2.4L Ecotec engine is partnered with a 6T40 transmission to deliver a great balance of performance and fuel efficiency.

Chevy Malibu Hybrid:
2008 MPG: 24/32
2009 MPG: 26/34
How it was done:
Malibu Hybrid delivers an estimated 34 mpg in city driving and 26 mpg in the city – an improvement over 2008 models, thanks to better control of the battery charging/discharging system and new low rolling-resistance tires.

More to follow - I'm sure!