Power to weight ratio is an important tangible aspect of any car when it comes to performance. But where is the point in which big horsepower prevails over a better power-to-weight ratio? Auto Express has provided an answer to that, by pitting the ultra-lightweight Caterham 360R versus the tech-heavy BMW M3 xDrive Competition, in a race around a racetrack.

BMW M3 xDrive Competition

The BMW represents modern-day performance saloons. It also happens to be the one everyone else in the segment measures against. Its S58, 3.0-liter twin-turbo inline-six engine puts out 503 horsepower at 6,250 RPM and 479 pound-feet (650 Nm) at 2,750 to 5,500 RPM. In the case of this one, power goes to all four wheels through the familiar, eight-speed ZF automatic.

All that modern tech, however, adds weight and the BMW M3 weighs in at 4,089 pounds (1,855 kg). This makes for a power-to-weight ratio of 217 horsepower per ton. Grip comes from Michelin Pilot Sport Cup 2 tires. The official 0 to 60 mph (97 km/h) time is 3.5 seconds, but independent tests have revealed times of under 3.0 seconds, for cars equipped with the xDrive, al-wheel-drive system.

Caterham 360R

The Caterham is the complete opposite of the BMW M3. It’s powered by a 2.0-liter naturally-aspirated inline-four engine that makes 180 horsepower and 143 pound-feet (194 Nm). Power goes to the rear wheels only, through a six-speed manual, which results in a 0 to 60 mph (97 km/h) time of 4.8 seconds.

All that simplicity and lightness translates to a curb weight of 1,234 pounds (560 kg) and a power-to-weight ratio of 321 horsepower per ton. Traction comes from Avon ZZS tires. It’s clear that the BMW is quicker in a straight line, but on a technical circuit, it’s as much about the chassis and weight as it is about the engine.

The track showdown

Both cars do a flying lap, which could be seen simultaneously, in the video below. Around the technical circuit, the much lighter Caterham should be at an advantage. However, the BMW is a force to be reckoned with, as seen by the lap times. In the end, the German performance sedan managed a time of 1:18.6 while the Caterham 360R was more than four seconds ahead, with a lap time of 1:22.8.

At the end of the day, the BMW M3 shows that, unlike in the old days when a car's power-to-weight ratio told the whole story, the turbo-torque, grip, and spot-on damping, secured a win for the BMW M3 Competition xDrive.