The saloon/sedan was offered in both the A8 (standard wheelbase), and the A8 L extended or long-wheelbase (LWB) version. The A8 L adds of rear legroom. Updates to the car in 1997 included the addition of six interior airbags. The A8 was designed as a competitor to fellow German rivals Mercedes Benz S Class and the BMW 7 Series. In 1997, Audi introduced the first series production electronic stability control (ESP) for all-wheel drive vehicles (Audi A8 and Audi A6)– the world's first production cars with both front and rear side airbags. For 1997, the new A8 was available with either front-wheel drive (FWD), or the Torsen-based quattro permanent four-wheel drive. The FWD models are powered by a 2.8-litre V6 engine, producing , and a 3.7-litre V8 engine producing , while the quattro received a 4.2-litre V8 producing . The A8 is available with standard luxury amenities, including dual-zone climate control, wood and leather interior trim, 14-way power and heated seats, and an enhanced Bose audio system. In 1999, Audi's flagship received side curtain airbags, new colours, and restructuring of option packages. The North American "warm weather package" added a solar sunroof which allows the interior ventilation fans to run, keeping the interior cool while the car is parked with the engine turned off. Changes to all models included a larger passenger-side mirror, and a first aid kit located in the rear centre armrest. In 1999 for the 2000 model year came a minor front-end restyle, with new, larger, clear headlights, a revised grille, and lower front valance with standard projection fog lamps. On the interior, the seats received a new, horizontal stitch pattern. Also, the 3.7-litre V8 FWD model was dropped, leaving the 2.8 V6 model and the long-wheelbase and short-wheelbase 4.2-litre quattro. These restyled cars also featured revised external door handles and an integrated radio antenna. For 2000, the North American A8 line-up was expanded to include the A8 L. In 2001, Audi introduced its new W12 engine, a compact 6.0-litre unit developed by effectively mating two VR6 engines together at the crankshaft.