Best camera to be placed high up to cover driveway (from 20ft) up ?

Not quite the same, but I managed to get a good deal (under £100/$100) on a - DS-2CD2645FWD-IZS

That is a 1/2.5" sensor size with 4mp resolution. It will be OK, but definitely not as good as a 1/1.8" (or larger) sensor size. So long story short, it isn't going to be a great "low light" performer. Hopefully you have some external light sources (street lights, flood lights, etc) that can help illuminate the area. If you do, this camera will probably work just fine. If you location is relatively dark without much external light, then you probably want to consider going with something else. A "bargain" isn't worth it if it doesn't provide good quality footage.