Useful car accessories

Spare lightbulbs

Let's face it, when the bloke behind you keeps honking his horn and you're convinced he fancies you, it's embarrassing to discover that he's actually trying to signal 'your brake light isn't working', and not, 'are you free for dinner?'. Pop a spare bulb for each light in the car and consult that handbook for how to change them. A full set costs about £10.