2015 Subaru WRX STI vs. 2014 Mercedes-Benz CLA45 AMG

Shootout at Road America


Go ahead, complain. We get it; this is an unlikely comparison. Highfalutin’ buyers interested in the Mercedes-Benz CLA45 AMG are probably unwilling to consider the plebian Subaru WRX STI. Likewise, Scooby enthusiasts are almost certainly disinterested in anything graced with a gigantic chicken-foot logo in the middle of its grille.

Pricing is another area where these two vehicles diverge. The Mercedes kicks off at $48,375; the STI is considerably more affordable, wearing a base MSRP of $35,290.

On the surface they may seem as different as chalk and cheese, as dissimilar as foundry coke and non-dairy whipped topping. But consider for a moment their similarities. Both the Benz and the Subaru feature potent turbocharged four-cylinder engines; in each car power is routed to all four corners through a cutting-edge all-wheel-drive system; and finally they both benefit from the latest go-fast technology. Perhaps they’re a closer match than meets the eye.

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The Boxer’s Knock-Out Power

Vital statistics matter; they’re just as important to gunshot victims in the ER as they are to vehicles in a dealer’s showroom. Suffice it to say, numbers count (literally and figuratively).

Starting with the Subaru, it’s powered by a brawny 2.5-liter boxer four-cylinder engine. This low-slung powerplant delivers 305 ponies with 290 lb-ft of torque. Variable valve timing, a block with semi-closed decks, a hardened crankshaft and 14.7 pounds of boost ensures ample muscle and long-term durability.

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A six-speed manual transmission is the only gearbox on the menu. It’s been specially reinforced to handle the STI’s extra power. If you want an automatic go buy a Prius.

Like every Subaru save the BRZ, this menacing four-door features the company’s famous symmetrical all-wheel-drive system. Aside from providing extra grip and added confidence in foul weather this technology is also beneficial on the racetrack, enhancing the front-heavy STI’s handling.

For even more fun the STI features a Driver Controlled Center Differential, DCCD for short. The mechanical limited-slip diff features three separate driver-selectable modes and more customization options than you’d care to read about. Summing this technology up, you can totally tweak how the vehicle handles by futzing with the center differential.

Naturally this performance car’s chassis has been thoroughly reworked as well. The springs, dampers bushings and attachments have all been redesigned and are stiffer than the previous model. Brembo brakes bring it all to a fade-free stop, time after time.

Subaru has thrown down an impressive gauntlet with their all-new WRX STI, but the folks in Stuttgart are not ones to be outplayed.

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Pocket V2 Rocket

Killing its rival’s buzz, the CLA45 AMG is armed with a 2.0-liter four-cylinder engine with the bores arranged in a more conventional configuration (read: inline). It may be down on displacement but this little wonder delivers 50 more horsepower than the Subaru and considerably more twist. Official figures clock in at 355 hp and 332 lb-ft of torque.

Thanks to turbocharging, direct fuel injection and a little bit of AMG magic this hand-built engine delivers V8-beating performance. Unlike the Subaru, which is only available with a manual transmission, this car is offered exclusively with an automatic. That’s too bad because a proper stick would be so much fun. But if you’re going to saddle drivers with a self-shifting gearbox it better be good, and the CLA45’s is cutting edge. It features a seven-speed dual-clutch unit for rapid shifts and maximum performance.

To deliver such generous output figures turbo boost tops 26 PSI, nearly double what the Subaru’s blower puts out. To keep cylinder pressures one step back from insane the compression ratio is a fairly low 8.6-to-1. Redline is 6,700 RPM.

A forged crankshaft and similarly formed pistons ensure a long lasting rotating assembly and shocking performance. The dash to 60 miles an hour takes a claimed 4.5 seconds; top speed is electronically limited to 155 miles an hour.

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High-performance 4Matic all-wheel drive puts power to the ground and supposedly weighs 25 percent less than competing systems from other automakers, and less weight is always a good thing in a performance car.

As for the rest of the CLA45 AMG’s chassis it’s significantly beefed up as well. The steering knuckles have been made stiffer, the bearings more rigid and bushings have been modified to transform the driving dynamics of this small sedan.

Showdown at Road America

Given their dissimilar hardware it should be no surprise these two cars drive differently. What’s surprising is just how unalike they feel. We were fortunate to test them back to back at Road America, a VERY fast four-plus mile circuit located in Elkhart Lake, Wisconsin, about an hour and a half north of Milwaukee.
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Starting with the Subaru, it’s loud and proud, always grumbling like a piece of agricultural equipment, but instead of bailing hay or harvesting corn this implement is all about speed. The characteristic boxer rumble is as prevalent as ever but it’s also augmented by some sort of whining sound at high engine speeds. It’s interesting combination.

As expected, acceleration is very quick, though gear changes are BRUTAL. Even in “normal” driving it’s almost impossible to shift the STI smoothly; the racing-grade clutch wants to grab like an angry toddler, but one with the hand strength of a Doberman’s jaw.

On occasion while navigating corners something funky would happen with Subaru’s front end. It felt like the differential was shifting torque around, though it would transmit a weird nibble into the steering wheel. The oscillation and accompanying noise only lasted a second or so but it was disconcerting when it happened at speed.

Compare Specs

2014 Mercedes CLA45 AMG
2015 Subaru WRX STI
Vehicle 2014 Mercedes CLA45 AMG Advantage 2015 Subaru WRX STI
Engine 2.0-liter Turbo Inline-4 - 2.5-liter Turbo Boxer-4
Horsepower 355 HP CLA45 AMG 305 HP
Max. Torque 322 lb-ft. CLA45 AMG290 lb-ft.
Transmission 7-speed dual-clutch automatic - 6-speed manual
Fuel Economy 23 MPG city / 31 MPG hwy CLA45 AMG 17 MPG city / 23 MPG hwy
Weight 3,494 lbs. WRX STI3,386 lbs.
Rear Legroom 27.1"WRX STI35.4"
Rear Cargo Capacity 13.1 cu. Ft. CLA45 AMG12 cu. Ft.
Starting Price $48,375 WRX STI $35,290
As Tested Price $55,925 WRX STI $39,290

Compared to Mercedes’ offering the Subaru felt like it had more suspension travel and consequently more body lean, though it was hardly excessive. The car still stays planted on the road.

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Other disappointing aspects of the STI include flat, tall and rather lifeless seats. This is a performance machine; it should cradle you in bolstering. Also, the car’s headliner looks awful, like a recycled cup holder you get from a fast-food restaurant, not that this is something that impacts how it drives.

Moving on to the AMG, its 50 horsepower advantage was obvious; it felt appreciably fleeter than the Subaru. It bursts ahead like a bottle rocket, just point it where you want to go, light the fuse and hang on.

Where the STI was raw the Mercedes was smooth, calm and daresay relaxed. The CLA45 is super easy to drive very, very quickly, just like other AMG models. It’s sort of a point-and-shoot experience though because the car’s ample technology can easily mask your mistakes making you look like a rock star even if you’re an American Idol reject.

Curiously the Benz sounds like it’s got gas. During hard acceleration up shifts are accompanied by a farting sound from the exhaust. We suspect it’s supposed to sound sporty but in practice it’s a little odd.

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And so is the brake pedal, arguably the least impressive part of this vehicle’s driving experience. The decelerator is extremely mushy, like stepping on a morbidly obese person’s clammy cankle. Even though the AMG has tons and TONS of stopping power it’s not very confidence inspiring because the pedal sinks half way to the floor before anything happens.

Also, under hard braking the Mercedes’ binders like to growl; think Chewbacca enjoying a shower head’s pulse setting and you’ll get the picture. Like the Subaru’s symphony of racket this muffled warble is somewhat unusual.

The Verdict

Wrapping all of this up with a pretty little bow, the CLA45 AMG is more fun to drive at speed than the WRX STI. It feels a good bit faster around Road America, its handling is more neutral, plus it’s smoother and more refined.

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Since it feels so raw the Subaru gives the initial impression that it is in fact the quicker machine, but after driving both of them back-to-back the Mercedes is definitely faster – particularily on this high-speed course. It wins you over with its predictability and ease of use, to say nothing of its sledgehammer punching power.

Still, the AMG is a lot more expensive plus you can’t get it with a manual transmission. If you want a performance bargain with a proper gearbox opt for the Subaru instead; it’ll reward years’ worth of smiles. However, if branding, outright speed and civility matter most, head on over to your local Mercedes-Benz dealer and check out the CLA45 AMG.

2015 Subaru WRX STI