Ford’s 1.0L EcoBoost I-3 Belongs Everywhere, Including in the Kia Rio

Maybe it’s because I’ve been hiding in the Motor Trend cube farm as much as possible, but the most memorable car I’ve driven this year has been the Ford Fiesta SFE EcoBoost. Sure, we’re not halfway through 2014, so there’s still time for another vehicle to catch my fancy. (C’mon, Mitsubishi Mirage.)

The Fiesta was memorable for exactly one reason: its new-to-the-U.S. 1.0-liter EcoBoost inline-three. I don’t think I spent enough words on the engine while writing the car’s First Test. It’s punchy when the throttle is opened, will empower hypermilers everywhere, and has an “up and at ’em” attitude you don’t expect from a 1.0-liter. (Turbocharging does wonders.) It’s a fine specimen, a prototypical template of the tiny-displacement engine prepped for the present and the farther-off future, and would make a great addition to basically every other automaker’s powertrain lineup.

It’s also selling faster than expected – accounting for 4 to 8 percent of the Fiesta mix, according to The Detroit News — despite all signs marking a disadvantaged spot in the marketplace. It can only be ordered, for now, on a subcompact vehicle, not a substantially better-selling compact. It’s an option on the SE trim only. A five-speed manual is the only transmission offered. Generally speaking, the majority of the driving public either has negative or zero experience with three-cylinders. And in the land where bigger is still better, there are places where locals will laugh (and not with you) if you announce your ride out front has a liter’s worth of swept displacement. That’s an inconvenient reality for the growing number of manufacturers attempting to boost Stateside three-cylinder acceptance.

In 2014, the car I’ve driven the most, without a lick of doubt, has been the long-term Kia Rio SX. It and the Fiesta SFE EcoBoost are super niche. Our Rio has the six-speed manual and that combination was only built for the 2013 model, at 459 total. After toying around, commuting, and living with the Fiesta SFE EcoBoost for a few days, I was thinking it’d be a blast if the Rio had the 1.0-liter EcoBoost. Here’s why.

The graph above represents the deceleration rates of the Fiesta SFE EcoBoost and Rio SX from 45 to 30 mph in each car’s top gear and the tallest non-overdrive gear. In the case of the Kia‘s six-speed transmission, fourth is technically the final non-OD gear at 1.04:1. But being a hair away from 1:1, the Rio was decelerated in third (1.29:1) as well. The speeds were chosen to emulate the roads around my home and the throttle-lift situation as I try to time the traffic lights without downshifting or braking, saving fuel. The benefit from a flatter curve is losing less momentum over distance, so there is more conserved speed as you get ready to accelerate right back up to 45 mph. As the curves demonstrate and the seat of my pants verifies, the Fiesta just wants to keep on rolling. Third-gear deceleration perceptibly feels similar to the Rio in its highest gear.

Naturally, the deceleration rates are affected by a bevy of vehicle variables, including aerodynamics (though the aero effect will be less pronounced at our selected speeds), the cars’ frontal areas, rolling resistance (different types and sizes of tires; the Fiesta runs a 185-width opposed to the Rio’s 205), and driveline friction can shift the curves in one direction or another. But the gas engines pumping with the throttle closed plays a major role in slowing down.

The second graph adds the speed over time curves of the two cars’ panic stopping from 60 mph, to highlight the power of good, old-fashioned friction brakes. Both didn’t take more than 3 seconds to come to a full stop.

With an efficient turbocharged engine less prone to wasting momentum, I’d have to imagine the Rio SX’s Real MPG of 30/40/34 mpg city/highway/combined would draw closer (maybe not dramatically so, but there’s room for improvement) to the Fiesta SFE EcoBoost’s 34/47/39 mpg. At the national regular-octane average price of $3.67 per gallon at time of writing via the U.S. Energy Information Administration, the Fiesta is in line to save nearly $1000 in fuel over 70,000 miles of driving. (Our spec cost of ownership mileage distance as determined by pricing partner IntelliChoice.)

In addition to the 1.0-liter engine, I’d even sub in the Fiesta SFE EcoBoost’s ride, alleviating the Rio’s occasionally thrashing motions from the rear end. A Rio SX with the Fiesta SFE EcoBoost’s engine and ride — now that would be a memorable subcompact I wouldn’t mind driving everyday.

Engine rpm change, as eyeballed on the tachometer

Ford Fiesta SFE EcoBoost

Third gear: 2950 to 1950 rpm (from 45 to 30 mph)

Fifth gear: 1700 to 1050 rpm

Kia Rio SX

Third gear: 3050 to 2050 rpm

Fourth gear: 2500 to 1750 rpm

Sixth gear: 1950 to 1250 rpm

Ford Fiesta SFE EcoBoost with Kia Rio SX photos by Robin Trajano