Benchmarks: Vitals and Battery Life
Power consumption between the two laptops is remarkably similar and CPU temperature under load has fallen off nicely. Neither ThinkPad gets particularly warm, and both have an internal fan that is practically silent at low load and reasonably quiet when the CPU is under the cosh.
Yet it's the last graph that's arguably most important for a modern-day Ultrabook. Our battery test entails looping a high-definition movie clip with 50 per cent screen brightness and flight mode enabled. In this scenario, the latest X1 Carbon was able to keep going for just over eight hours. That's still shy of the desired 10-hour mark that some Ultrabooks are able to hit, but it represents a significant improvement over previous models in Lenovo's range and the cherry on the cake is that the battery employs 'rapid charge' technology, allowing it to get back to 85 per cent in just over 30 minutes.
It's worth bearing in mind the battery in the 2012 laptop isn't going to be in prime condition, and the capacity of the battery in the 2015 model is fractionally higher, but nevertheless, a 2x increase in longevity is very welcome indeed.