The stock A4 is a good-looking car - the new one even more so. It does the job it's designed for, and stylishly too. The shortened front body overhang makes it look purposeful, while the longer bonnet and wheelbase lend the impression of being a large saloon. With a Cd value of 0.27, it's aerodynamically efficient too, and can easily take a volume of 480 liters of luggage to boot. The new A4 is offered in India with a choice of two engines, 3.2FSI petrol and a 2.0TDi diesel. Both engines are direct-injection types. 
Depending on engine spec, you can choose from a range of 16, 17 or 18-inch alloy wheels. Optional xenon plus headlights make for improved visibility at night. The Audi A4 DTM on the other hand is a very different beast all together. If the standard car can be termed a cat, the DTM version would probably be a saber-toothed tiger, and that's why it's so menacingly successful on the track. It's about performance, power and handling. It's the fourth-generation Audi A4 DTM, and is known as the "R14" internally at Audi Sport. The DTM version is built around a steel DTM Touring Car space frame made of aerospace industry grade steel, with the driver's safety cell being made out of very strong carbon fiber composite, as used in F1. As accidents tend to happen at a much higher speed on the racetrack, for the driver's safety, the front and rear crash structures are also made of the same material. It's 4800 mm long, 1850mm wide and 1200mm short. The standard A4 is, in comparison, 4586mm long, 1772mm wide and 1427mm tall. 
The engine of the DTM A4 is not available in the road car that you drive in India - it's a normally aspirated (no turbo or supercharging) 4000cc V8 engine with a 90deg angle between the cylinder banks. It breathes through four valves per cylinder, and despite the mandatory intake air restrictors, still develops approximately 460bhp of power and over 370 lb/ft of torque. It's a rear-wheel-drive car and power to the rear wheels is transmitted via a 3-plate carbon-fiber clutch and a sequential 6-speed sport gearbox. To keep the power delivery honest, the A4 DTM has an adjustable limited-slip plate differential and constant velocity sliding type tripod universal joint shafts.
Aerodynamics plays a huge part in car racing and it's also the case in DTM. As in F1, when a part falls off (and parts can fall off in DTM as the cars go body-to-body into a corner trying to muscle each other off) the car's performance is compromised. But like an iceberg, there is more aerodynamic trickery under the car than can be seen - along the underbody of the car, air passages, slots and steps abound so that air pressure under the car can be harnessed to make the A4 DTM stick to the road like a leach clings to skin. The cockpit of a DTM car is very different too. While the standard car's cockpit is given to creature comforts, a DTM driver's cockpit, or workplace if you like, is a stark contrast due to its multitude of gear shift lights, rev counter, indication of engaged gear, lap timer, speedometer, etc. Switches, buttons, digital displays, as well as traditional levers and pedals characterize an A4 DTM cockpit. Did I mention the buttons? 
You have buttons for the radio (for pit to car communication, not AIR FM Rainbow) and for activating the speed limiter in the pit lane. More buttons for selecting headlight high beam and activating the drinks supply. The left paddle behind the steering wheel actuates brake valves for the parking brake. The right hand side paddle actuates brake caliper cooling! The sequential gearbox is actually manually operated. There is no AC, so adjustable inlets for fresh air into the cockpit have been provided for the driver. Then there are even more buttons, for adjusting brake balance, the display brightness, and, handy after a crash, the fire extinguisher. You have the main electric switch, with ignition and starter buttons on the right and a hazard warning light system for when the car stalls on the grid.
Once the buttons have been memorized, there is the rest of the A4 DTM. It has a servo-assisted rack and pinion steering, front and rear independent double-wishbone suspension, a pushrod system with spring/damper units, adjustable gas pressurized dampers and a hydraulic dual-circuit brake system that actuates light alloy brake calipers on ventilated carbon brake discs at both front and rear. The driver can adjust the brake balance to his or her liking. The A4 DTM runs on Dunlop SP Sport Maxx tyres, 265/660 R18s mounted on 10x18inch aluminum forged rims at the front, and 280/660 R18s mounted on 11x18in rims at the rear. With the driver included, the total weight of the car is 1,050kgs.
Obviously, such a purpose-built racer will never see Indian roads, except perhaps during a blue moon. The whole exercise is a demonstration of Audi being ‘Vorsprung durch Technique' or ‘ahead thanks to the use of technology,' which describes Audi's effort in DTM perfectly - they're leading the series.