Merc-AMG A45 S vs Audi RS3: 0-120mph battle

Mercedes-AMG A45 versus Audi RS3. Now there’s a head-to-head we want to conduct. But we haven’t – yet. Instead, I wanted to show you just how evenly matched the two are – and how deeply fast each is as well. Yes, I know the A45 is all shiny and new and has 20bhp more than the Audi, so before we go any further let’s have a look at why that doesn’t automatically give it a speed advantage.

It has 369lb ft of torque, which, from a 1991cc swept volume is remarkable (read the first drive for all the engine facts). From an extra cylinder and 489cc the RS3 ‘only’ manages 354lb ft. But it’s on tap at 1,700rpm, and at that point in the rev range the A45 is only delivering a little over 200lb ft.

Of course you’re never at 1,700rpm when you’re launching, but the fact remains that the Audi – purposefully – delivers its torque low down and then sustains it pretty much to the red line. The A45 – equally purposefully - doesn’t. Instead AMG designed the power curve so that torque didn’t peak until 5,000rpm, meaning the acceleration is constantly building through the mid-range. Doesn’t help acceleration times, does improve the sensations you get in the car.

Don’t want to spend too long on geekery. What also helped the RS3 was its weight (at 1,530kg, 20kg lighter) and the fact it was tested on a cool day (8 degrees) in the UK. The A45 was tested last week in Spain where the temperature was 30 degrees higher. Good for sticky-tyre traction, less good for efficient engine combustion – imagine how hard the intercooler is having to work.

Anyway, here are the numbers:

                        A45                  RS3

0-10                 0.55                 0.61
0-20                 1.11                 1.09
0-30                 1.69                 1.56
0-40                 2.27                 2.13
0-50                 3.00                 2.79
0-60                 3.85                 3.64
0-70                 4.87                 4.75
0-80                 6.09                 5.94
0-90                 7.47                 7.25
0-100               9.04                 8.88
0-110               11.04               10.62
0-120               13.43               12.71
30-70               3.18                 3.19
30-100             7.35                 7.32
¼ mile             12.42s             12.26s
@                     114.8mph        117.2mph

Braking

100-0               87.50m                        87.75m
60-0                 32.40m                        32.12m

Now tell me these two weren’t benchmarked against each other. A solitary 0.01secs in it from 30-70mph? A mere 0.03secs difference to cover the 70mph gap from 30 to 100mph? I reckon a cool day in the UK might see an extra 0.1secs taken off the A45's 0-60mph, and maybe a couple by 100mph. Merc-AMG claim 3.9secs to 62mph. Audi claims 4.1secs, but RS3s – in fact all Audi RS cars – under-promise and over-deliver (we’ve timed RS6s to 60mph in 3.3secs).

So we’ll have to get both cars together on the same track at the same time and see what happens. Fireworks, it’s safe to assume given that both are faster to 100mph than any BMW M2 or M3 (blame the rear-wheel drive). Other notable scalps include the Toyota Supra, Bentley Bentayga, Caterham 620S, every Merc C63 apart from the Edition 1 C63 S Coupe and every Porsche Cayman up to and including the GT4.

I’ll leave you to delve into the figures if that’s what oils your wheels, but it’s also worth pointing out that their stopping distances from 100mph were separated by less than the length of a wheel spoke.