Comparing claimed speeds of the "fastest car(s) in the world", especially in historical cases, is difficult as there is no standardized method for determining the top speed, nor a central authority to verify any such claims. The current title Guinness World Records holder, the Bugatti Veyron Super Sport, was certified for the average top speed achieved on a two-way run, registering km/h (mph). While only 5 of the World Record model were made, the Super Sports will achieve this speed with the limiter turned off. Guinness, after a review by a panel of experts, consider this not to be a modification and thus it is eligible for this list.