1999 V6 Rodeo LS 4wd on 135k miles.
Uses 1 quart of oil ~600 miles - if you own a Rodeo CHECK THE OIL OFTEN. It's a design defect in the pistons, well known issue, not a "problem" as such, just buy oil in bulk from CostCo and keep it topped up. It holds 5 quarts, if it drops down below 2.5 quarts, your transmission will shift very harshly and you'll be 50% down on power. Those are the warning signs, ignore them and you'll bleed cash, but DON'T take your Rodeo to the mechanic and tell him your transmission is shifting harshly UNTIL you've tried topping up the oil - otherwise he'll convince you your tranny is toast and pull your pants down on the cost.
The transmission (4 speed auto) is otherwise silky smooth, despite having no dipstick it's checkable and re-fillable. Mine has lasted about 50k miles so far. If the number lit up on the dashboard (P, D,R,1,2,3) is not equal to the gear that you're in, then you have to take the shifter apart (under the car) and clean up the contacts in the shift position selector, common problem to watch out for.
City mileage is around 15/16 mpg, less if you boot it frequently (powerful engine, very tempting). Highway ~20mpg @ 75mph, ~25 @ 55mph (but you'll only get that if you drive an entire tank (450 miles or so) on the highway with a cop behind you)
Costs: new front brake pads fitted & machined rotors will cost around $200, because it's 4wd, and the locking front hubs complicate matters. Also, replacing CVs (inevitable in any car after 100k miles) will cost $600+ if you have the 4x4, because the front transfer case has to be dropped. only buy the 4x4 if you really need it. It's not a full time 4x4 anyway, and you can't use it on dry pavement. Tires cost me $600 for 4 new all seasons at Costco.
Lots of squeaks and rattles, don't take them to heart - it's a body on frame SUV, it's meant to talk to you. My hood has started squeaking on left hand turns, sounds like the suspension is about to collapse. It might well be, who knows, that's all part of the fun :)
Conclusion: a ten year old car, unless it's Honda or Toyota, is going to need maintenance. I feel sorry for the folks who bought these things new (wow, $30K, that's serious!) but as a $4k vehicle, for people with the right car-repair mindset, the Rodeo now represents excellent value for money.
Mine will get me through any snow-storm, up (and down!) any gradient, will pull as much as a 3.2L V6 can be expected to pull (4000 pounds), will cruise on the highway, fit into city parking spaces, has excellent visibility, is safe (airbags, ABS, SOLID frame), looks cool (my opinion), looks cooler the more dents it has (again, my opinion) and is cheap to insure.
All in all, a great used car deal.