I can tell you about our experience. On our last trip we rented a Nissan Xterra 4X4 from Econo. I had booked it online and got an excellent rate...after using the 10% discount on the Visitaruba discount card (you can find information on it at www.visitaruba.com) we wound up paying $315 per week. We wanted a 4X4 on our last visit, and since there were 5 of us in our party, we needed something big enough for all of us. (It did have A/C...for me personally, I couldn't imagine NOT having it in Aruba...it gets very hot. However, some people do prefer the Jeep Wrangler with the top down...not for me though.).
The people at Econo were very pleasant and helpful. The vehicle itself was in pretty sorry condition, BUT it did get us where we were going. The tires were terribly worn (and that's putting it mildly), but we did make sure that they took note of all of the weak points of the vehicle on our contract. Well, low and behold, on the day when we were going to be 'adventurous', we went out to the parking lot, and sure enough, had a flat. My husband called the emergency # and within 10 minutes they came and changed the tire. The windshield washer was not working, and when my husband told them, they asked him to follow them to a nearby garage where they fixed it. Well, I say that loosely...it worked one time after it was 'fixed'. The electric windows were temperamental as well. God only knows how many miles this vehicle had on it...the gauge was either disabled or broken. Upon our return of the vehicle, they were apologetic and offered us an additional $15 off of our bill for the inconvenience.
They said that they only had a couple of the Xterras in their fleet (they were NOT new...we saw a few others in parking lots, and they didn't look much better).
Would we rent from them again? We probably would if we needed a large vehicle again(which we most likely will again...our kids have a habit of wanting to return to Aruba with us! Hmph!). However, it is possibly that on our next visit we might need something to accommodate 6 people, so we'll have to look elsewhere.
The only other place we've rented from was Dollar (we rented vans in the past)...I'm not sure that they are even still in business though. There, too, the vehicles seemed to in pretty sorry shape.
Two companies that I have heard rave reviews about are Tropic (but unfortunately they only seem to offer small cars) and Janssen (they have the Kia you were talking about). You might want to e-mail them and ask if it is a 4X4 or a 2X2.
Check out these sites:
Good luck in your search.