A car, driven by a twat. Often an older boy racer/ girl racer who now has a job as a sales rep or a similar moderately successful occupation.
The car is often a BMW or Audi, although many other 'prestige' vehicles can fall into this category. Said vehicle may be a fine driving machine but has a poor image amongst the general public, due to many of the owners driving them aggressively and without any regard for either road laws or the safety of other road users.
Studies have yet to be undertaken, but it it is a commonly held view, that this poor driving is due to the owners belief, that owning a 'superior' vehicle gives them the right to drive in such a manner. Furthermore, owners (or twats) are reluctant to accept any criticism of their vehicle or driving and attribute such criticism as merely jealously from the drivers of inferior vehicles.
etymology - believed to have evolved from the shamefully term 'spaz-chariot.' This was used in Britain to describe the small motorised invalid carriages ,which used to be provided by the state to disabled people.