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2015 Ford Mustang EcoBoost 2.3 First Test

New Turbo-Four Tested, Dyno'd

Carlos Lago
Sep 17, 2014
Photographers: Courtesy of the Manufacturer, William Walker
The most amusing thing about the new Mustang is evident when you pop its hood. Here's the longest-running name in the musclecar business, looking all mean and modern and ready for the 21st century. And what do you see in its engine bay? Space.
That space produces a consistent response from people who've just said, "Hey, is that the new Mustang?" Their next comment: "A four-banger?" Perhaps the EcoBoost's greatest downfall is that it demands explanation every time you pop the hood. If you're buying one, here's a cheat sheet: lower weight, better fuel economy, and 320 lb-ft of torque.
Photo 2/96   |   2015 Ford Mustang EcoBoost Front Side View
Weight? Our automatic-equipped EcoBoost Premium weighed 146 pounds less than the manual GT we tested, and 96 pounds of that came off the nose. Unfortunately, Mustang weight has crept up this generation, and this EcoBoost model is up 128 pounds versus the last V-6 Performance Package we tested.
Horsepower has increased by 5 versus that same V-6 (though new V-6s are rated another 5 hp lower), but torque has increased substantially, up 40 lb-ft. Lean in over the 2.3-liter inline-four, peer over the passenger side, and there, sitting underneath a bit of heat shielding, is the twin-scroll turbo helping supply that power with 18 psi peak boost -- if you believe the gauge.
In the case of our test car, a six-speed automatic routes that power to a 3.55:1 final drive and locking rear differential, then out to two 9 x 19-inch wheels shod in 255/40 Pirelli P Zero tires. Those parts come with a $1995 Performance Package that also adds beefier braking hardware (13.9-inch rotors/four-piston caliper front and 13.0-inch rotors/single-piston caliper rear) and a larger diameter rear anti-roll bar.
Yes, we wished for a manual, but the auto was the only option available, and it acquitted itself nicely in our testing. With stability control off and the car in Track mode, a launch involved holding both pedals, waiting for boost to surge, and releasing the brake. It's an amusing process, and produced a best 0-60 mph time of 5.6 seconds and a quarter-mile pass of 14.1 seconds at 97.8 mph. The upsized braking hardware and P Zero tires produced a best 60-0 mph stop of 106 feet, with the other three stops hovering in the 107-foot range. Those acceleration results beat the GTI by 0.1 second, but fall short of the potential speed from a WRX launched as if you've stolen it.
The Mustang posted a 25.5-second lap time around the figure eight, tying the WRX but trailing the GTI by 0.4 second. At an average 0.96 g laterally, the Mustang tied what we recorded from the GTI.
Considering the lack of weight on the nose, we expected a bit more nimbleness than this Mustang offered. It stops authoritatively and allows aggressive corner entry. Exits are fun, too; the car digs out of corners with a nice amount of stability. But mid-corner behavior is disappointing -- the car's attitude feels somewhat soft and soggy, offering a mild understeer that's difficult to adjust. Where the GT likes being adjusted with the throttle -- the instant-on V-8 torque allows you to counter the chassis' tendency to push -- the turbo doesn't allow this option.
Our figure eight exacerbates this mid-corner behavior. In real-world driving, where turn radii, elevation, and surfaces change, the Mustang was more enjoyable. Jump on a sweeping on-ramp, feed in boost while you dial in that nicely weighted steering, and it's easy – and fun – to push yourself and the car harder.
The turbo makes neat whooshes when the hood's open, but unfortunately you don't hear them from inside the cabin. The noise you do hear sounds somewhat mechanical and not unlike the Focus and Fiesta ST. It's aggressive, if not sing-songy.
Photo 21/96   |   2015 Ford Mustang EcoBoost Interior
The interior design matches the sharp exterior. You can sense the Mustang traces in the layout, but controls and screens feel modernized -- amusingly, the speedometer is labeled Ground Speed. The driver's seat offers great forward visibility, and you can use the hood's visible creases as reference markers. The shifter falls easily under your hand, as do all the steering wheel-mounted controls.
There are quite a few of those controls. Our EcoBoost was fully loaded, with heated and cooled seats, adaptive cruise control, dual zone climate control, and so on. Though the Premium trim started at $29,996 and totaled $37,660 after options, dropping items such the adaptive cruise control ($1195), that automatic ($1195), and a few others makes sense for enthusiasts. But if you're going down that route, the non-Premium EcoBoost starts at $25,995, cutting out satellite radio and the options mentioned above.
Photo 22/96   |   2015 Ford Mustang Ecoboost Dyno Graph
But let's get back to that turbo-four, shall we? The best way to picture how an engine responds is through a power/torque graph such as the one above. If all you care about are peak figures, we recorded 279 hp on run three and 295 lb-ft of torque on run four. During five runs, output remained consistent. Torque stayed above 290 lb-ft for four out of the five runs, varying around 3 lb-ft. We're showing the chart with the best horsepower.
One thing of note: That dip in power around 5700 rpm appeared on all dyno runs. We're curious to find out what it is.
During testing of this turbo-four we noticed a strong mid-range but a soggy top end. The dyno chart confirms this sensation. Note that power builds immediately; torque arrives solidly at 3200 rpm and hovers in the high 280 lb-ft range until 5200 rpm. This means the engine feels responsive and rather powerful around the city, where it spends most of its operating range in that sweet, meaty torque range.
Photo 23/96   |   2015 Ford Mustang EcoBoost Front Side View Parked
Stretch the tach upward, though, and once peak horsepower arrives at 5300, it's all downhill after. The last thousand rpm feel soft, and as a result, wringing it out during limit-handling tests or straight-line acceleration can feel a little unsatisfying. Short-shifting is an entirely viable option.
Surprised by the lack of high rpm grunt? You shouldn't be. Look at power/torque graphs of the Focus and Fiesta ST and you'll see a very similar shape, though at lower numbers. Clearly, this engine was developed with a similar mindset. And, well, look at how much we love that Fiesta ST.
Overall, the EcoBoost makes a very pleasant non-V-8 entrant in the Mustang lineup, matching the performance of similarly priced enthusiast cars, provided you option it reasonably. It's by no means a replacement for the V-8, but nor is it the penalty box the V-6 used to be. Its higher fuel economy rating and strong low-rpm power delivery make it a compelling choice as a fun, sporty daily driver.

2015 Ford Mustang EcoBoost
BASE PRICE $25,995
PRICE AS TESTED $37,660
VEHICLE LAYOUT Front-engine, RWD, 4-pass, 2-door coupe
ENGINE 2.3L/310-hp/320-lb-ft turbo DOHC 16-valve I-4
TRANSMISSION 6-speed automatic
CURB WEIGHT (F/R DIST) 3658 lb (53/47%)
WHEELBASE 107.1 in
LENGTH x WIDTH x HEIGHT 188.3 x 75.4 x 54.4 in
0-60 MPH 5.6 sec
QUARTER MILE 14.1 sec @ 97.8 mph
BRAKING, 60-0 MPH 106 ft
LATERAL ACCELERATION 0.96 g (avg)
MT FIGURE EIGHT 25.5 sec @ 0.80 g (avg)
EPA CITY/HWY/COMB FUEL ECON 21/32/25 mpg
ENERGY CONS., CITY/HWY 160/105 kW-hrs/100 miles
CO2 EMISSIONS, COMB 0.78 lb/mile
Photo 30/96   |   2015 Ford Mustang GT Ford Mustang Ecoboost Front Three Quarters In Motion

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