Ealing's alright. No more gun crime than any other middle of the road suburban London borough though its more than 10 years since I last lived there. It's getting worse though with loads of the people from the surrounding areas coming into the area. It used be a place for artists, novelists and the like - Ealing comedies, the theatre and so on. I always thought Acton (S,E) was rougher including the area around the High Street and the Estates. But North Acton towards Park Royal is quite upmarket - £500k - £1M+ houses etc.
As to the car, I suspect they did some running on it. Bonnet > Roof > Shed (or the other way round) a bit like that that building jumping craze where people leap from one rooftop to another. When I was in living in Pimlico/Millbank I was woken up at about 2am in the morning by screaming and laughing, looked out of the Window and these youths, all one after each other, were running across the top of about 10 cars, bonnet > roof > bonnet of next car > roof etc jumping from one car to the next.
BTW you can't really slash your legs to ribbons by trying to kick through a widescreen - it either collapses as an entire piece or a hole gets punched through it if the force is strong enough (a kick with the sole of the foot or both feet wouldn't generate enough force) and because its laminated (very thin plastic layer) or shatterproof glass you dont get shards of glass like a house window.