- Engine: The 2007 328i has a larger 3.0-liter inline-six engine, while the 2006 325i has a smaller 2.5-liter inline-six engine. The 3.0-liter engine produces more horsepower (230 vs. 184) and torque (200 lb-ft vs. 175 lb-ft) than the 2.5-liter engine.
- Transmission: The 2007 328i has a standard six-speed automatic transmission, while the 2006 325i has a standard five-speed manual transmission. A six-speed automatic was optional on the 2006 325i.
- Fuel economy: The 2007 328i gets an EPA-estimated 20 MPG in the city and 30 MPG on the highway, while the 2006 325i gets an EPA-estimated 19 MPG in the city and 27 MPG on the highway.
- Price: The 2007 328i was more expensive than the 2006 325i, with a starting price of $33,100 compared to $29,400.
- Features: The 2007 328i came with a number of standard features that were not available on the 2006 325i, including a power moonroof, heated front seats, and automatic climate control.
