INGOLSTADT, Germany — Audi's RS6 Avant is no slouch in the performance department, with a twin-turbo 5.0-liter V10 that will get you to the grocery store or soccer camp in lightning-quick fashion.

Hard on the heels of Motoren Technik Mayer's recent take, the RS6 Avant also gets special scrutiny from two famed German tuning houses, Christian Abt's Abt Sportsline, based in Kempten, and Siegfried Becker and Michael Bentler's B&B Automobiltechnik, based in Siegen-Birlenbach.

Abt takes the RS6's already smoking V10 (572 horsepower, 479 pound-feet) and gooses it to 691 hp and 590 lb-ft of torque. Zero-to-60-mph acceleration is trimmed to less than 3.9 seconds, and top speed is inflated to 199 mph.

The Abt package also bundles a suspension-lowering kit, 20-inch alloy rims, quad tailpipes and the usual aero add-ons, plus an assortment of cockpit dress-up items.

Like MTM, B&B has elected to offer several different stages of tune for the RS6, starting at 641 hp and ranging up to 705 hp. B&B claims its high-end edition will rocket from zero to 60 mph in less than 3.6 seconds, with velocity peaking at 199 mph.

B&B fits a performance exhaust system and, like Abt, reprograms the ECU. Just for fun, you can order B&B's tailpipes in chrome, carbon or matte black finishes.

Ride height is lowered by 1.0 inch with the standard suspension upgrade, and B&B also offers a special threaded chassis with several stages of precise adjustment for handling geeks. Alloy wheels in sizes up to 21 inches are available.