2005 Audi S4 vs. 2004 BMW 645
To start off, 2005 Audi S4 is newer by 1 year(s). Which means there will be less support and parts availability for 2004 BMW 645. In addition, the cost of maintenance, including insurance, on 2004 BMW 645 would be higher. At 4,398 cc (8 cylinders), 2004 BMW 645 is equipped with a bigger engine. In terms of performance, 2005 Audi S4 (339 HP @ 7000 RPM) has 11 more horse power than 2004 BMW 645. (328 HP @ 6100 RPM). In normal driving conditions, 2005 Audi S4 should accelerate faster than 2004 BMW 645. With that said, vehicle weight also plays an important factor in acceleration. 2004 BMW 645 weights approximately 20 kg more than 2005 Audi S4.
Because 2005 Audi S4 is four wheel drive (4WD), it will have significant more traction and grip than 2004 BMW 645. In wet, icy, snow, or gravel driving conditions, 2005 Audi S4 will offer significantly more control. With that said, do keep in mind that many other factors such as speed and the wear on your tires can also have significant impact on traction and control. Let's talk about torque, 2004 BMW 645 (451 Nm @ 3600 RPM) has 41 more torque (in Nm) than 2005 Audi S4. (410 Nm @ 3500 RPM). This means 2004 BMW 645 will have an easier job in driving up hills or pulling heavy equipment than 2005 Audi S4.
Compare all specifications:
| 2005 Audi S4 | 2004 BMW 645 | |
| Make | Audi | BMW |
| Model | S4 | 645 |
| Year Released | 2005 | 2004 |
| Body Type | Station Wagon | Convertible |
| Engine Position | Front | Front |
| Engine Size | 4163 cc | 4398 cc |
| Engine Cylinders | 8 cylinders | 8 cylinders |
| Engine Type | V | V |
| Valves per Cylinder | 5 valves | 4 valves |
| Horse Power | 339 HP | 328 HP |
| Engine RPM | 7000 RPM | 6100 RPM |
| Torque | 410 Nm | 451 Nm |
| Torque RPM | 3500 RPM | 3600 RPM |
| Engine Bore Size | 84.6 mm | 92 mm |
| Engine Stroke Size | 92.8 mm | 82.7 mm |
| Fuel Type | Gasoline - Premium | Gasoline - Premium |
| Acceleration 0-100mph | 5.6 seconds | 6.1 seconds |
| Drive Type | 4WD | Rear |
| Transmission Type | Manual | Manual |
| Number of Seats | 5 seats | 4 seats |
| Number of Doors | 5 doors | 2 doors |
| Vehicle Weight | 1795 kg | 1815 kg |
| Vehicle Length | 4580 mm | 4830 mm |
| Vehicle Width | 1790 mm | 1860 mm |
| Vehicle Height | 1450 mm | 1380 mm |
| Wheelbase Size | 2660 mm | 2790 mm |
| Fuel Consumption Overall | 13.4 L/100km | 12.8 L/100km |
| Fuel Tank Capacity | 66 L | 70 L |
