There was a time when the competition between different engine makers in Formula 1 was just as exciting as the battle between car designers. Would one car manufacturer be able to unleash some amazing horsepower, and steal a march over a rival whose chassis may have been slightly better but whose power unit was lacking?
Remember the awesome BMW V10s of the early noughties and how they helped Williams take the fight to Ferrari? Or the Honda powerplants of 20 plus years ago that helped both Williams and McLaren secure world domination?
The inevitable curbing of costs in F1 resulted in an engine freeze, which at the time of the introduction of the latest-generation V8 engines appeared to signal the death knell for power-unit development. But the reality has been slightly different.
This week, Mercedes-Benz threw opened the doors of its High Performance Engines (HPE) factory at Brixworth to a select group of media, and the tour delivered a fascinating insight into just how modern power units are still very much a defining factor in F1.