2007 Chevy Trailblazer - mid size SUV

[brucepick]

2007 Chevy Trailblazer - mid size SUV
4.2 L I-6, 4WD, auto transmission

EPA:
- 14 mpg city, 20 mg highway, 16 mpg combined
Actual driving mpg, mixed city/highway:
- 21.29 mpg (307 mi, 14.42 gal)

Why review a SUV that won't even make 25 mpg?? This is a fuel economy forum after all. Well, we needed a big beast of a car for a 300-mile road trip and rented this one. I figure I can share what I learned. As it turned out, in true mixed driving it got better than the EPA highway estimate, without any special techniques aside from very slightly boosted tire pressure. Not too bad.

I won't attempt to review every aspect of the car but I can comment on the fuel economy and on a few other things we noted.

Most notable was that we realized just over 21 mpg in true mixed driving while the EPA numbers are 14/20. As much as I dislike SUVs ingeneral, I thought that was a pretty good showing for this large beast of a car. I didn't spare the horses. I think that if you need a large vehicle like this you would likely get similar results. Handling was good; I found it to be pretty nimble and stable when turning and cornering.

The 4.2 liter I-6 (Ecotec) is the smallest of three engines available for the 2007 version of this car. I found it far more than adequate for our needs. When I wanted it to get up and go, it did. In fact my two loving passengers asked me to lay off the gas pedal a bit.

the 4WD is switchable via a little electrical knob in the dash. Options are:
2wd high (rear drive!), this gives the best FE out of the available choices
4wd high
4wd low
Neutral (what for??)
Automatic 4wd. This keeps part of the transfer case gear engaged however no power to the front wheels. When the computer detects a loss of traction it engages 4wd immediately. Probably a good compromise setting if you want 4wd only when needed.

We rented this for a trip from CT to New York City; just over 300 miles round trip. Our son was traveling with us, and at 6'7" nearly all back seats are uncomfortable for him. This car did give him enough room in the back seat.

The trip included a good amount of true city driving in New York City, which I expected would really take a toll on the overall mpg. I used no special driving techniques and in fact on the return trip I drove faster and more aggressively than I usually do because my son had to get back home for work. I didn't baby it on the first leg either; with wife and son along I wasn't going to use any hypermiling techniques. We had rain on the trip in to NY and dry roads for the return trip.

I did add some air to the tires. Spec was 30 psi front, 35 rear. I set them at 32/36. Sorry, I just couldn't buy the 30 psi spec. Usually I see front tires spec'd for higher psi if not the same as the rears. My understanding here is that the higher pressure rear spec is to accommodate the full rated load capacity of the vehicle, whatever that is. Front weight of course is pretty consistent based on engine + drive gear weight.

Comfort and conveniences -
My son and I were comfortable. My wife, sitting in the front passenger seat, found the seat belt uncomfortable. The steering wheel had adjustable tilt but I did not find a front/rear adjustment for the wheel.

There were three front cup holders however none of them was actually comfortable and convenient for me to use while driving. Climate control was good, separate temperatures for left and right front positions and another set of controls for the rear seating area. Rear cargo area was quite spacious. We just tossed in a few items of clothing and such however it would certainly handle 6-8 pieces of luggage and probably more.

[kamesama980]

I worked at a dealer on and off the last couple years. Trailblazers are pretty inefficient since they have all the downsides of an SUV (bad mileage, big tires, bad visibility) and less cargo space than a minivan. About as spacious as the chevy cars for passengers. oyea, and terrible in snow. Almost hit a few things driving a brand new one around town in powder. in 4hi it handles worse than my rwd 5-speed cressida in the snow and accelerates about the same.

[Mike T]

Originally Posted by brucepick

Automatic 4wd. This keeps part of the transfer case gear engaged however no power to the front wheels. When the computer detects a loss of traction it engages 4wd immediately. Probably a good compromise setting if you want 4wd only when needed.

This setting is useless; any decently designed 4WD will apportion a certain percentage of drive to the secondary axle at all times, which gives the vehicle a more stable driving behaviour. 40%-60% would be in the "normal" range. The 0%-100% split systems like this one, that use viscous couplings to shunt power from front to rear, actually upset the stability of the vehicle when you would most need it to be predictable - namely when one or more wheels is slipping.

I have driven some of these on compact snow and it isn't pretty at all. Accelerating from rest, the rear wheels spin like mad, crabbing the car sideways, at which point the fluid in the VC heats up and makes the front end bite, which pitches the car in another direction, then power is shunted back to the rear in a slightly smaller dose...... and so on..... in an interative fashion until the thing is up to speed and marginally in control. Comapring and contrasting that with full time 4WD is like going from a nightmare to a walk in the park.

Full time 4WD would be technically superior, although theoretically reducing fuel economy.

[kamesama980]

the trailblazer uses a RWD base platform and transfer case like any truck. automatic 4wd engages the front hubs but NOT the transfer case. when rear wheelspin is detected, it engages the transfer case and you have 4x4 faster than going from 2 to 4x4. either way, it sucks on the snow. straight line accel is better on my cressida with RWD and 50 psi tires.