A sense of style is one thing that a lot of time travelers have in common. Many of them build their time machines to look like various time machines out of fiction, with the blue police box, Delorean, and whirling clockwork seat being the most popular.
This wouldn't mean much except that it has some really curious repercussions on the DMC Delorean and British police boxes. You see the law of conservation of events makes it extremely difficult to create a paradox. This alone shouldn't mean much, except when combined with the fact that time travelers eventually get ahold of every DMC Delorean ever produced and the vast majority of blue British police boxes.
This means that it is almost impossible to destroy either one of those objects unless it has already been converted to a time machine. Attempts to destroy them will certainly fail in the case of a Delorean and will almost certainly fail in the case of a police box. Several different travelers have experimented with Deloreans and discovered it is basically impossible to blow them up, drive them off a cliff, launch them into space, sink them into the ocean, or even to wreck them decently. The bomb won't go off, the car will break down before it can even get near the cliff, the space launch won't go off, or the car will come through the accident basically unscathed.
London police boxes are not quite so indestructible as Deloreans, because not all of them have established futures as time machines, at least not yet. They are still very difficult to demolish though, and will usually resist multiple attempts at destruction, but with enough effort they can be destroyed, even if the specific box did have a future, as time will simply conspire to give that same future to another police box.
Fledgling time travelers looking to travel in style are advised to seek out a police box, as a Delorean cannot be sourced anywhere other than another time traveler, although it is rumored that some of the fake prop Deloreans used in theme park rides are still available. By the time 2015 rolls around there won't be a single authentic Delorean or police box left on earth, although there are still hundreds of police boxes that can be rescued before their destruction.