Like other carmakers, BMW wants to be as environmentally friendly as possible and one of its methods is to find ways to reuse the energy waste that is produced, whether it's heat or from braking. BMW engineers are currently trying to determine the best methods to harness the power that comes from heat. Their goal is to eliminate cold start and generate energy from reusing exhaust gasses. Andreas Eder, BMW Heat Management Pre-Development Projects chief, said that they aim for cars to warm up as quickly as possible, since higher temperatures mean less friction, less friction means less fuel consumption and, therefore, less CO2 is produced.
In one BMW prototype, the engines were encapsulated and were completely surrounded by clad walls and panels in order to eliminate cold starts. However, converting exhaust into energy isn't as simple. BMW is developing a thermoelectric generator that was presented last year but still needs some more modifications. So far, the tweaks made to it since, allow for up to 250 W to be produced in normal driving conditions, half of the on-board electricity used by a 5 series. The principle used by the generator is the so-called Seebeck Effect (the effect of the temperature gradient in thermoelectric semi-conductor elements generating electrical voltage). In short, the temperature difference is directly proportional to the outputted voltage.
Some aspects of the technology are already made, such as the air flaps in a few current models, however, the technologies are largely considered to still be under development. This research has so far produced advancements such as the longer cooling time of the engine (40 degrees after 12 hours since stop), or the elimination of the electrical heating modules. These are definitely in the direction of getting better mileage and reduced emissions in future vehicles.