Another day, another upgraded supercar: hot on the heels of yesterday's news of the Mercedes SLS AMG GT comes news of more power for the McLaren MP4-12C.

The 2013 Model Year car goes up from 600 PS to 625 PS from 3.8 litres. That means it is almost the same as the original McLaren F1, which had 627 PS from its 6.1 litre V12 – that is a measure of the increase in engine efficiency over the last 20 years (and the benefits of turbocharging).

McLaren famously insists the MP4-12C is the most efficient sports car in the world – it scores a maximum 12 points (hence the name) on McLaren's own efficiency rating. Now it says that the revised model is "even faster on-the-limit with no loss in efficiency". However, in an apparent nod to all those road testers who say that ultimate efficiency is actually the problem with the car, the Intake Sound Generator (ISG) now allows "programmable aural drama inside the 12C cockpit."

We would like to have been present when someone tried to explain to "Mr. Efficiency" Ron Dennis, overlord of McLaren, that extra drama was required, even though it added nothing that could be quantified in terms of performance.

The good news for existing owners is that they will be offered a series of free upgrades to make their cars almost 2013 specification:

• engine power increased to 625PS
• Revised calibration for 7-Speed SSG transmission
• Programmable Intake Sound Generator
• Headlights linked to rain sensor when in automatic mode
• Easy-Exit electric seat function incorporating Seat Return (if specified)
• New Meridian audio equaliser settings (if specified)

You don't get offers like that on a 12 month old family hatchback.