The recent cold weather, down to -5C near me, seemed to have given my car an extra 20hp. I assume it’s the cold dense air going into the engine giving it the boost. No idea how it all works really.

Another upside of the frosty weather is that my car looks rather good with a white roof.

The air going in to the intake will be colder and slightly denser, yes, but the gain is probably more from the air cooling the intercooler and thus the air after the turbo. Some rally cars (and others over the years) have used water sprays on the intercooler to give the same effect. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

As above, and a further 'improvement' is to be had when the air is moist, similar to misty conditions. More beneficial if running big carbs, not so on modern electronically controlled injection systems.


Dave 2010 3.6 TDV8 HSE (Gone)
2011 Discovery 4 Commercial SDV6 (Gone)
1980 OBLIC 4.0ltr Range Rover (went a long time ago)

I haven't seen a graph of power output vs temperature. The power drop on my TDV8 is noticably reduced during the warmer months of the year (based on driving it for 12 years).