Two-stage driver and front-seat passenger frontal airbags are standard, as is Audi's "side guard" head protection curtain airbag system. This latter system completely covers all of the side windows, from the front 'A pillar' to the rear "C-" or "D pillars". The body-hugging Recaro shell-type RS race bucket seats (not available in North American markets), complete with electrically inflatable upper and lower side bolsters and adjustable lumbar support, are constructed so as not to need lower side airbags to comply with European crash safety standards. In North America, the only front seats available are the more traditional Recaro seats (identical to those in the B6 and B7 S4), which include lower side airbags; these were also available as a no-cost option in other markets. Lower side airbags are optional for the standard-fit Recaro rear seats. Front and outer rear seatbelts include pyrotechnic belt pretensioners, whilst all belts include an excess load limit function.