Three car seats for kids aged 1.5 to 7 don't really sit side by side in a mid-size SUV like a Sorrento.
Its stupid, really. Hefty, booster seats from reputable brands seats have integrated cup holders.
Cup holders.
Also, consider that a 1.5 year old's rear facing car seat is a steel reinforced monstrosity. The thing is so big, I cant install it behind the driver seat because I cant extend the seat back (Im 1-1.5 stdev above average american height).
So, the third kid's booster chair with a seat belt aligning backrest (needed for the younger kids so that the belt doesn't sit on the kid's neck) simply doesn't fit. Not if you want to reach the belt buckle.
For short trips I usually just have the oldest go booster-less. For longer trips I install the chair while she's sitting, buckled on the chair. I then lift her and the seat and muscle them in. Finally, I can pull the straps to tighten the booster chair to the backseat.
My SUV is not small. There's plenty of room. But we all drive like maniacs (guilty as charged, btw) so our kids need these massive steel reinforced cocoons.
So, why trucks? Trucks, and SUVs on truck frames (ford expedition, suburban), are wider.