For those trackside, the biggest obvious change since the end of the 2013 season has been F1's new, milder engine note.
For the drivers, however, the major talking point is 'torque'.
The V8 engines of last year, and the radical new generation of ERS-bolstered turbo V6s, are actually producing similar overall power.
But the torque of the 2014 'power unit' is significantly higher.
Force India's Adrian Sutil had an even starker experience.
"When I accelerated out of the corner, I was surprised," said the German, recalling his first moments with the Mercedes-Benz V6.
"I changed from third to fourth gear, lost the rear and I spun."
Works Mercedes driver Nico Rosberg agrees: "The driveability with the turbo is a little bit of an adventure!"