What determins a car's "turning circle"

Trying to decide if a large MPV will be too hard for us to drive around town but in fact it has a smaller turning circle than our existing estate.

Can anyone tell me what determins the turning circle of a car. How can a much larger vehicle have a considerably smaller turning circle than a smaller car?

And then, if a large vehicle has a small turning circle does that mean it will be as easy to park/manouver as a smaller car?

Thanks

Depends on how acute an angle the front wheels can turn and the overhang at front and back. My old Citroen Picasso had a much bigger turning circle than a much longer Mercedes E Class estate, the Mercedes is about 2 feet longer. Rear wheel drive cars tend to be able to turn their front wheels to a greater angle but thats a bit of a generalisation and doesn't apply to all.

I would say it is a combination of the distance between the front and rear axles and the angle towards 90degrees that the front wheels can turn away from straight on. The nearer to 90 deg that the wheels can turn the smaller the turning circle. SLim