2009 Audi S4 vs. 2007 BMW 645
To start off, 2009 Audi S4 is newer by 2 year(s). Which means there will be less support and parts availability for 2007 BMW 645. In addition, the cost of maintenance, including insurance, on 2007 BMW 645 would be higher. At 4,398 cc (8 cylinders), 2007 BMW 645 is equipped with a bigger engine. In terms of performance, 2009 Audi S4 (340 HP @ 7000 RPM) has 12 more horse power than 2007 BMW 645. (328 HP @ 6100 RPM). In normal driving conditions, 2009 Audi S4 should accelerate faster than 2007 BMW 645. With that said, vehicle weight also plays an important factor in acceleration. 2007 BMW 645 weights approximately 760 kg more than 2009 Audi S4.
Because 2009 Audi S4 is four wheel drive (4WD), it will have significant more traction and grip than 2007 BMW 645. In wet, icy, snow, or gravel driving conditions, 2009 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, 2007 BMW 645 (450 Nm @ 3600 RPM) has 40 more torque (in Nm) than 2009 Audi S4. (410 Nm @ 3500 RPM). This means 2007 BMW 645 will have an easier job in driving up hills or pulling heavy equipment than 2009 Audi S4. 2007 BMW 645 has automatic transmission and 2009 Audi S4 has manual transmission. 2009 Audi S4 will offer better control over acceleration and deceleration in addition to better fuel efficiency overall. 2007 BMW 645 will be easier to drive especially in heavy traffic.
Compare all specifications:
| 2009 Audi S4 | 2007 BMW 645 | |
| Make | Audi | BMW |
| Model | S4 | 645 |
| Year Released | 2009 | 2007 |
| Body Type | Convertible | Coupe |
| 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 | 340 HP | 328 HP |
| Engine RPM | 7000 RPM | 6100 RPM |
| Torque | 410 Nm | 450 Nm |
| Torque RPM | 3500 RPM | 3600 RPM |
| Engine Compression Ratio | 18.0:1 | 10.0:1 |
| Fuel Type | Gasoline | Gasoline - Premium |
| Drive Type | 4WD | Rear |
| Transmission Type | Manual | Automatic |
| Number of Seats | 4 seats | 4 seats |
| Number of Doors | 2 doors | 2 doors |
| Vehicle Weight | 930 kg | 1690 kg |
| Vehicle Length | 4580 mm | 4830 mm |
| Vehicle Width | 1780 mm | 1860 mm |
| Vehicle Height | 1400 mm | 1380 mm |
| Wheelbase Size | 2660 mm | 2790 mm |
| Fuel Consumption Overall | 15.7 L/100km | 11.8 L/100km |
| Fuel Tank Capacity | 63 L | 70 L |
