We’ve tested the mega-hot-hatch Mercedes-AMG A45S before, so this time I subjected the poor car to some different testing criteria…
What’s new in this model?
Umm, the headlights! And maybe the dashboard screen or digital instrument cluster, which, no doubt, now have some sort of A.I. guide to help you navigate through the endless abyss or menu options. Until you select reverse gear or dare to open the driver’s door, then the whole shebang will either disappear or yell at you.
Power is identical to the white 2021 model we tested a few years ago: 310kW and 500Nm from a mere 2-litre turbo-charged engine. Those sorts of numbers would’ve sounded crazy 10 years ago, absolutely preposterous for a previous generation and in most of the 20th century, you would’ve been burnt at the stake for such a claim.
But it is, of course, absolutely true. The boffins at AMG spent a considerable amount of time getting north of 420 horsepower from a 2L motor. It’s not the first time a production engine has achieved this (see also: Honda S2000) and it appears that most 45 AMG engines seem to last; if you don’t drive like a teenager.
All-Wheel Drive
Another reason these 45 models are so blisteringly fast is that Mercedes-AMG ships them exclusively with an extremely clever 8-speed dual-clutch (automated manual) transmission, and that sends every available horsepower to all four of the car’s fat tyres… via the quick and adaptive 4Matic+ all-wheel-drive system.
In plain English, that means you should think twice about taking on any A45 S from the traffic lights, because its turbocharged engine produces monster power which is quickly and ferociously transferred to the road… to leave anything less than a supercar or dual-motor EV gasping for breath and/or eating dust.
Race Start
Its manufacturer claims that this car can catapult itself from a standstill to 100km/h in a ridiculous 3.9 seconds – no thanks to a brutal launch control function called “Race Start” – and we were all-too-happy to test that claim on a cool and quiet night in 2021. Our best attempt yielded a still-impressive 4.05 seconds.
What makes that Ferrari-scaring data so appealing is that the car feels solid and tight enough to repeat the rather strenuous process a few times in a row, although I would caution hot-headed owners against trying it more than a handful of times in quick succession. And to keep up the maintenance, as these cars run rather tight engineering tolerances.
Typing of which, that finally brings me to the point of this article, which is basically the written version of a video I filmed with this matt grey winged and finned monster you see before you. And it comes to you in the shape of a question: what happens when you purposefully drop out of this car’s power band?
Power band
Before I go any further, I’d like to reiterate that this was not to take any shots at AMG, the A45 or modern performance vehicles. When driven normally, especially in fully automatic mode, the scenario you’re about to see is pretty much impossible. It’s part of the reason why this car is such a weapon: it’s been designed to operate at peak levels most of the time.
And this is where things got a bit difficult for me because it turns out that no other fool in the world had tried this slightly pointless exercise before. I’m happy to report that the video got plenty of positive comments on our parent company Galimoto Media’s YouTube channel, some even encouraging us to do more of the same.
I spent a considerable amount of time searching for power and torque graphs of the current A45 S but could only find two examples of the previous vehicle; one from a dyno company and the other compiled by an Australian publication. These formed the basis of my hypothesis: that this engine needs to “spool up” before it reaches its full potential.
High-rpm torque curve
That is fairly normal for any petrol motor, even turbo-charged ones, but the 45 engine has something which is rather unusual for a modern turbo-petrol engine: its torque (or twisting power) does not arrive at the acceptably low norm of 1,500 or even 2,000rpm but instead appears near the manic motor’s red-line of 7,000rpm.
This was very encouraging because, together with eight gear ratios and a manual override function, I was sure that I could keep this engine off the proverbial boil. And before you condemn any 45 AMG power plant for this shortcoming, it wasn’t just out of its comfort zone but was also put it into an elite group of turbo-lag heroes; like the Ferrari F40 or Porsche 911 930 Turbo.
And so, without further ado, here is the video we filmed, followed by a comparative table of acceleration times, which brutally highlights the difference between a full Race Start with maximum rpm upshifts, or my silly little test where I shifted into the next gear as soon as possible, and thus struggling around below 2,000 or even 1,500rpm.
| 2021 Full rpm | 2024 Low rpm | |
| 0-10km/h | 0,31 seconds | 0,66 seconds |
| 0-20km/h | 0,69 seconds | 1,14 seconds |
| 0-30km/h | 1,05 seconds | 1,71 seconds |
| 0-40km/h | 1,41 seconds | 2,27 seconds |
| 0-50km/h | 1,78 seconds | 2,98 seconds |
| 0-60km/h | 2,12 seconds | 4,19 seconds |
| 0-70km/h | 2,50 seconds | 7,38 seconds |
| 0-80km/h | 2,98 seconds | 14,88 seconds |
| 0-90km/h | 3,50 seconds | 27,82 seconds |
| 0-100km/h | 4,06 seconds | 39,88 seconds |
| ¼ mile time | 12,19 seconds | 21,27 seconds |
| ¼ mile speed | 116,84 mph | 52,59 mph |
Comparison conclusion
Again, I can’t stress enough that this comparison is merely for demonstration purposes, because it only takes the press of a button for the off-boost beast from 2024 to turn into a full snorting dragon. It’s also worth noting that, although I didn’t use launch control, the initial (0-50/60km/h) times were quite smart as I was desperately trying to upshift at that point.
The most telling difference is obviously in the higher speed range, where the 2024 car was laboring around 1,200rpm from 90 to 100km/h in an agonizing 12 seconds; an increase in momentum which took the full-boost car less than half a second!
So, the next time you find yourself cruising alongside a slumbering A45 S, and the driver has inexplicably selected eighth gear and manual mode, your Renault Kwid or Volkswagen up! stands an extremely good chance of pulling away from a new AMG! Until he goes back into normal Drive or Sport mode.