This was the first V6 car we bought, we were too afraid of fuel cost but this car uses almost the same amount of fuel as a V4 Camry does. In two years of ownership from 130k to 161k miles, apart from tires, brakes, battery etc we only had to deal with check engine lights (cylinder misfire) that would come and go. Tune-up and new plugs and wires would fix the shaky ride and fix the light for the time being but it kept coming back on (would drive fine though). The airbag light also came (same on another 99 Solara SLE 112k we bought later). The car would still drive very smoothly. The drive is so smooth that we wouldn't realize and we'd be cruising at 70mph in 55 zone! Got 20-22 mpg cty/hwy mix
Even with check engine lights it never stranded us and always kept us going! Excellent, super comfy ride, decent gas mileage compared to V4 Camry of the same year (our 97 and 01 Avalons gave 26+ mpg with the same/similar 3.0 engine but they are not as sporty).
Reliable airbag sensors, ECM/computer. Our SLE V6 seemed to have a bad computer. My Mom has a back problem and didn't find the passenger seat comfortable, it could be just her.