2005 Audi S4 vs. 2003 BMW 645
To start off, 2005 Audi S4 is newer by 2 year(s). Which means there will be less support and parts availability for 2003 BMW 645. In addition, the cost of maintenance, including insurance, on 2003 BMW 645 would be higher. At 4,398 cc (8 cylinders), 2003 BMW 645 is equipped with a bigger engine. In terms of performance, 2005 Audi S4 (340 HP @ 4000 RPM) has 30 more horse power than 2003 BMW 645. (310 HP @ 6000 RPM). In normal driving conditions, 2005 Audi S4 should accelerate faster than 2003 BMW 645. With that said, vehicle weight also plays an important factor in acceleration. 2005 Audi S4 weights approximately 87 kg more than 2003 BMW 645. So despite on having greater horse power, its additional weight may have an impact towards its acceleration in comparison.
Let's talk about torque, 2003 BMW 645 (450 Nm) has 40 more torque (in Nm) than 2005 Audi S4. (410 Nm). This means 2003 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 | 2003 BMW 645 | |
| Make | Audi | BMW |
| Model | S4 | 645 |
| Year Released | 2005 | 2003 |
| Body Type | Station Wagon | Coupe |
| Engine Position | Front | Front |
| Engine Size | 4172 cc | 4398 cc |
| Engine Cylinders | 8 cylinders | 8 cylinders |
| Engine Type | V | V |
| Valves per Cylinder | 5 valves | 4 valves |
| Horse Power | 340 HP | 310 HP |
| Engine RPM | 4000 RPM | 6000 RPM |
| Torque | 410 Nm | 450 Nm |
| Engine Bore Size | 85 mm | 92 mm |
| Engine Stroke Size | 93 mm | 82.7 mm |
| Engine Compression Ratio | 11.0:1 | 10.5:1 |
| Number of Seats | 5 seats | 4 seats |
| Number of Doors | 5 doors | 2 doors |
| Vehicle Weight | 1785 kg | 1698 kg |
| Vehicle Length | 4550 mm | 4830 mm |
| Vehicle Width | 1770 mm | 1860 mm |
| Vehicle Height | 1430 mm | 1380 mm |
| Wheelbase Size | 2470 mm | 2790 mm |
| Fuel Consumption Highway | 11.2 L/100km | 8 L/100km |
| Fuel Consumption City | 15.7 L/100km | 16.1 L/100km |
| Fuel Consumption Overall | 13.8 L/100km | 10.9 L/100km |
| Fuel Tank Capacity | 66 L | 70 L |
