Little wonders: Mercedes's new AMG tearaways aren't held back by smaller engines

It’s not unheard of for car manufacturers looking for extra speed and grunt in sportier versions of their existing creations to opt for a single concept upon which to base everything else around – they take a base model and stick a bigger engine in. However, clearly mindful of the fact that this kind of approach is becoming frowned upon by those who’d quite like polar bears to still have somewhere to live in 10 years' time, the technical types at Mercedes-Benz have opted for a more modern option with their latest AMG creations – they’ve stuck a smaller engine in. Yes, the new A45 S and CLA 45 S, the first a hot hatch and the second its saloon sibling, are powered by four-cylinder, turbocharged, two-litre power plants. Hang on, we hear those of you who are less concerned about the habitats of our seal-loving friends cry, how much fun is there in that? Well, remarkably, the answer is a lot. Both vehicles have been completely redesigned and fitted with the kind of innovative tech we’d have all been stunned by not so long ago. They have what’s known as a 4Matic+ system. It’s complicated and largely to do with axles, but the result is not difficult to comprehend – you can go round corners really fast. The first clue as to what these two could be capable of was in the venue where the manufacturer chose to introduce them to the world – the Jarama race track in Madrid, the former home of the Spanish Grand Prix. It doesn't take someone with the intellect of The Big Bang Theory 's Sheldon Cooper to work out that when a car maker unveils its latest offerings at a motorsport circuit, they're going to be showing you something with a little more speed and agility than an electric scooter. Anything that has an AMG moniker emblazoned on the paintwork is going to be zippy, but the figures for the new model are impressive by any standards – the A45 S can do 0-100 kilometres per hour in 3.9 seconds with an electronically limited top speed of 250kph (which you can have increased to 270kph if you have the bottle). Marginally slower is the CLA 45 S, which has the same maximum whack but will hit the ton in four seconds. Let’s face it, though, you’d have to have some superhuman, bullet-time sense to be able to notice the tenth of a second difference. All that power, and they’re still less harsh to our ursine friends’ living quarters than the V8 monster housed in many a 4x4. Mercedes has managed to grind 355bhp out of those positively tiny engines and it shows. One of the main ideas behind the A45 S and CLA 45 S is that they can be used to pick up the youngsters from school and do the family shop after allegedly responsible adults have spent time roaring round a race track in them. A Mercedes engineer in situ in Spain revealed that the new cars had largely been designed with this very concept in mind. The thing is, a lot of people would love to see what their motors can do around a circuit, but most wouldn't bother as this kind of thing tends to eat through tyres rather more rapidly than a trip to the swimming pool might (assuming, of course, your day-to-day motoring isn't too inspired by the Mini jockeys in The Italian Job ). However, our German technical friend claimed that a key design feature of the new AMGs was that they should be able to do at least 10 laps of the Nurburgring before a change of tyres is needed. For those not in the know, that’s a race track in Germany with a public-access circuit (the Nordschliefe) which anyone can take a road-legal vehicle out on. Each lap is just over 20km in length, so, in total, that’s a decent amount of payback for your Michelin rubber and considerably more than you’d get out of most cars, hyper, super or otherwise. The AMG fleet at Jarama took a proper hammering, too. There was no controlled driving here. The only limit on how fast you could go was how brave you were and the speed of the pace car in front, whose driver was busy giving tips via walkie talkie on how not to go airborne and wrap your ride round the nearest piece of track furniture. So, the tearing-it-up-on-the-circuit side of things is all good then. What are they like when you turn off the sport plus button and take them on to the open roads? Well, the inside is as comfortable as you’d expect from any car of this sort, and the console, while complicated, is very pretty to behold and has just about every piece of information on it you could possibly imagine. We’ve mentioned the power already, but both cars ride smoothly at the lower end of the rev range. Pootling through the Fuencarral-El Pardo hills north of Madrid in rides of this sort is little short of breathtaking. Enough about Europe though – these cars will arrive in the Middle East in December. The A45 S will cost $67,000 (Dh250,000) and the CLA 45 S $70,000 (Dh260,000), excluding VAT. What Mercedes has achieved with these vehicles is significant, and this is probably the way in which most cars with a sporty edge will be designed in the future. You can be impressed by all the technical innovations and revel in the drama of it all. Or, like a lot of us, just be extremely happy you can go round corners really fast.

Little wonders: Mercedes's new AMG tearaways aren't held back by smaller engines

The A45 S and CLA 45 S growl and rip up the road like furious marmots, but, now, all that power is coming from a positively moderate source