I just purchased a 2006 H3 with 48,000 miles. So far I am really happy with it. When doing research on this vehicle I found the towing weight is 4500lbs. I have a circle track car and trailer that weigh about 4300lbs. I will tow them about 50 miles round trip twice a month. Has anyone else towed this much weight? Any problems? Suggestions? I am a little concerned with only a 3.5L 5 cylinder. Thank you.

 

The max I've towed is close to 3000 pounds. But I've read of people towing 4500 pounds with no problem on a straight and even road. Only problem is driving on uphill roads. But if it is only a 50 mile round trip you should be fine with 4300 pounds.
Goodluck!

 

I had a 2007 H3 with the 2.7 I5 and I towed a trailer with vehicle and trailer weight in excess of 12000 lbs from Va to Ak with no problems. The gas mileage went down to 8-9 dependig on the roads but it trucked right along. I know this exceeded the towing capacity of the truck but it was a lease vehicle and I had no intent on keeping the truck past the lease end. I currently have a 2009 H3T Alpha and towed a trailer vehicle combo from AK to AL with no problems coming south, mileage was about the same.

 

I don't think it is an issue, unless it is a very hot and humid day, then you might see the temp climb.

Add a trans cooler and have at it.