Used Jeep Buyer's Guide
Just driving a new car off the dealer lot typically results in an instant several-thousand-dollar loss of value. So maybe you've decided to go with a used '07-present Wrangler or Wrangler Unlimited (four-door) to save a few bucks. Many people often wrongly believe that they should avoid the first year of a new model. In some cases it can be a good move, but the truth of the matter is that there are often continual running changes made throughout the model years. For example a mid-year '08 may be pretty much the same as an early '09.
The '07 JK has an advantage, or disadvantage, depending on who you talk to. From 2008 on, the Wrangler received tire-pressure monitors in the wheels. The sensors are expensive (compared to a common rubber valve stem), and the system can be a pain in the ass when aftermarket tires and wheels are swapped on. However, the system can be altered or completely deactivated with aftermarket controllers, so don't let it be a deciding factor. We have an '07, so of course we're a little biased.
For pure off-road capability,...
For pure off-road capability, you'll want the two-door Wrangler. However, if you plan to use the rear seats much, you're better off with the four-door Unlimited model.
Besides the tire pressure monitor, available colors and minor trim pieces, there really are not that many changes from '07-'10. All of these Wranglers have the same 3.8L engine, all of them have the same six-speed manual or four-speed auto, and all of them have the same reliable NV241 transfer case and axles unless you opt for the Rubicon model. With that you get Dana 44 axles all around and a 4:1-geared NV241OR transfer case. Most JKs have 4.10 axle gears, although a few will have the less-desirable 3.21 gears. The six-speed manual tranny will typically get about 1 mpg better fuel economy over the optional four-speed automatic. If you're going to hack your new JK up anyway and plan to swap the engine, tranny, T-case, axles and so on, then maybe look for a good deal on a two-wheel-drive version. Overall, the real difference will be in how well the '07-present Jeep in question has been treated and maintained.
As with any used car purchase, check the basics. Inspect the engine and automatic tranny oil. Does it smell burned? Is it really dirty from poor maintenance? Is it foamy from water contamination? Are the tires worn, is there any visible body damage, are there missing parts, and so on.
A few undercarriage scrapes...
A few undercarriage scrapes and dings are normal. But move on to the next Jeep if most of the paint is dragged off, the exhaust is severely dented, or the crossmember and suspension brackets look like they've been beaten by a pack of sledgehammer-wielding monkeys.
Look for and avoid Jeeps with mud and other debris packed into strange places, especially in the interior. Check the vents, under the carpet, and anywhere that might lead you to believe it's been left out in a flood or hurricane to become a submarine. If you see any signs of submersion, it's best to find a different Jeep.
Looking at the underside of a Jeep is a good way to understand its history. Eyeball the front end from a distance. Do the tops of the tires lean in? Bigger tires and speedy off-road adventure in a JK can result in a bent front axlehousing. Are the framerails and crossmembers packed with mud? Is the muffler dented? Do the control arm brackets, frame, and crossmembers look bent, twisted, and jagged like they've been dragged over an industrial cheese grater? Have the track bar brackets been broken off and rewelded? If so, the Jeep shouldn't fetch top dollar. There are plenty of clean JKs out there, so don't fall in love and pay full price for a Jeep that's not like new.
Check the hard top parts. Do they look like they have been removed and tossed around by gorillas at the airport? Are the seals cut, worn, missing, or damaged from poor handling and storage? Do the soft top window zippers function properly? If the doors have been removed and poorly handled, you'll notice paint chips missing around the hinges and the outside edges.