The weight of the vehicle is only relevant when hitting another vehicle or unsecured object. Most non at fault accidents involve hitting another vehicle, so this is important! If you mean smaller in size, then the smaller the car is, the less space there is in front of you and behind you, and this makes the vehicle less safe in an accident. Short hatch backs are deadly for rear passengers in rear end accidents.
High riding vehicles often do roll over when in a severe accident on the corner (small overlap crash).
Rolling over is quite common in a crash, but in city crashes usually the speeds are so low by the time it rolls over that it is not dangerous.
As you can see, real world bumpers are a lot different than the honeycomb thing that they use in the side impact crash test. They hit higher up, and in the real world the car being hit as also moving.
They’re higher up, so in city driving they’re better at protecting the passengers in a side impact crash when hit by another SUV. Such vehicles roll over more easily than cars do, so on divided highway driving they’re more dangerous than a car. But still not as bad as a real SUV or truck. Roll over accidents on Interstate highways are very common. A messed up lane change or merge in can send a vehicle sideways in to the center divider or off the road where it will usually roll over if it’s an SUV. It’s very dangerous because it’s still usually going fairly fast, like 40+ MPH, when the roll over starts. A young girl around here went in to a roll over accident at 70 MPH in an SUV and nearly died. Most of the divided highways around here don’t have outside guard rails and many don’t have center dividers.
Tesla has a very low center of gravity and is least likely to roll over, along with the Corvette.
One important feature to prevent roll overs is Electronic Stability Control. It’s an addition to the ABS that will apply the brake on the opposite wheel if the vehicle makes an uncommanded turn to one side. It helps prevent a lot of loss of control accidents on divided highways. If another car hits the back side of your car and sends you at a 45 degree angle off the road, ESC isn’t good enough to save you though. But it helps a lot in more minor mishaps.
Before ABS it used to be possible to apply the brakes and skid the front wheels. This will force the car to keep going straight even if it is sliding sideways. If you get hit in the rear and you react fast enough you could save the car from going off the road. The rear wheels will keep turning and straighten out the rear. Now ESC does this for you, but not quite all the way.
The car hit a corner. A sturdy concrete corner. It hit close to the middle, hitting the rear wheel drive engine directly, where the car is strongest. The crash is much different from a transverse engine in a front wheel drive car.
The body guard was wearing a seat belt. He was also sitting in front of what was probably a powerful first generation airbag. The kind that will decapitate a bady in a rear facing child seat. The kind that hold a full grown man without bottoming out in a 35 MPH crash test with no seat belt. The kind that stays inflated for a fraction of a second longer after deploying so it can still protect you in a secondary collision. I believe the body guard would have almost certainly been killed in a typical late model single stage airbag equipped full size Toyota / Kia / Honda / Ford / Chevy vehicle.