I am thinking of buying a 2007-2008 trailblazer, i know nothing about these, I was wondering what type of gas mileage you guys were getting out of these in the city and highway??? I am looking to buy a 4wd also.. straight 6 i guess these have in them, will they pull a trailer and a polaris ranger with no difficulties, the combo is close to 4,000 pounds??? are there any major problems with the years i am inquiring about??? I guess more pros and cons of them would be nice. Hope some can shed some input. Thanks in advance.