The class-leading standard engine in the 2007 TrailBlazer was the award-winning Vortec 4.2L I-6, which produces 291 horsepower (217 kW) and 277 lb.-ft. of torque (375 Nm). The Hydra-Matic 4L60 electronically controlled four-speed automatic transmission was matched with both the Vortec 4.2L and Vortec 5.3L engines. Regulated voltage control was new for the Vortec 4.2L and Vortec 5.3L engines. It enhances fuel economy by reducing the load on the engine generated by the alternator. TrailBlazer uses hydroformed steel frame side rails, which form a strong foundation for the trucks’ overall strength and solid feel, even on unpaved surfaces. A five-link rear suspension and independent, double-A-arms up front work with a system of 12 specially tuned body mounts using hydraulics and rubber pads to dramatically reduce vibration and harshness on any kind of road or trail. Four-wheel ventilated anti-lock disc brakes are standard. An Autotrac four-wheel drive system is standard on 4WD models. The 2007 TrailBlazer with the Vortec 4.2L I-6 (LL8) engine and 4WD gets 15 MPG city, 21 MPG highway, and 20 MPG combined. The TrailBlazer (4.2L) with 4WD has a trailer towing maximum of 6100 lbs. I hope this information is a start. If you have further questions, please feel free to contact me directly. Thank you.
Tricia, GM Customer Service.