2015 Ford F-150: Fuel Economy Test: 2.7-liter EcoBoost vs. 5.0-liter V8

by Dan Edmunds, Director of Vehicle Testing on May 6, 2016

Some months back I had this great idea for a fuel economy test. Would our 2.7-liter EcoBoost V6 really do all that much better than a 5.0-liter V8 when tested in the real world away from the controlled confines of the EPA test dyno? At the time, our 20 mpg-rated 2.7-liter EcoBoost 4x4 had averaged just 16.4 mpg with some 18,000 miles under its belt, a figure that trailed the 17-mpg combined rating of a 2015 Ford F-150 4x4 with the 5.0-liter V8 engine.

EPA ratings notwithstanding, this question was not without merit. We were not the first to complain about EcoBoost fuel economy, and our man Jay suspected this boiled down to a fuel enrichment strategy that's necessary to keep the turbos and exhaust system cool, a move that'd use extra fuel. Ford's 5.0-liter V8 wouldn't need to employ such tactics because, well, it has no turbochargers.

So I obtained a Lariat 5.0-liter crew cab 4x4 that was very similarly equipped to ours. Mark Takahashi and I drove them both on three different test loops totaling 692 miles. To eliminate variables we followed one another at a respectful distance, swapped between the trucks, took turns in the lead and used the same gas station fuel pump at the beginning and end of each loop.

It was perfect.

But storm clouds began brewing after I analyzed all the data and sat down to write the summary. I changed the oil in our 2.7-liter EcoBoost V6 and discovered that, unbeknownst to me, it contained 10 quarts of oil instead of the required 6 quarts during the test.

*face palm*

I thought I was done for. I was sure Mark and I had wasted all of that time and effort, in fact. But after I corrected the oil volume I decided to wait and see after the truck accumulated another 10,000 miles. At the end I studied the truck's average fuel economy before, during and after the overfilled period and decided the extra oil had made no meaningful difference in fuel consumption.

I was back in business.

So here we are. These are the previously-withheld results of my Ford F-150 2.7-liter EcoBoost V6 versus 5.0-liter V8 fuel economy comparison test.

As you can see, the trucks looked nearly identical. And they were. Both were Lariat-trimmed SuperCrew 4x4 pickups. They rode on the exact same tires and wheels. You can't see it, but both had the optional 36-gallon fuel tank, towing package ingredients and tailgate step. They even wore the same Blue Flame metallic paint and shared the black accents and body-color trim of the Lariat Sport Appearance package.

But there were a couple of differences. Our attempt to create the perfect truck match-up was not 100-percent perfect.

On the "who cares?" side of the ledger you'll find the bedliner. Ours had a body-color Line-X spray-in bedliner, the 5.0-liter V8 loaner had the factory black spray-in version. The challenger had the FX-4 off-road shocks, skidplates and stickers package, ours did not. Our truck was equipped with the Lariat 501A package, heated leather buckets, a Sony CD radio upgrade and optional touchscreen navigation while theirs had the slightly more well-equipped Lariat 502A package, which bundles all of that stuff with LED headlights, cooled front seats, heated rear seats, a heated steering wheel and a few other odds and ends of little consequence to the question at hand.

There were two differences that may have mattered. Our truck had the optional trailer towing mirrors while the 5.0 V8 was blessed with normal-sized ones. Our 2.7-liter EcoBoost was also fitted with the optional 3.73 axle ratio instead of the standard 3.55 setup. Meanwhile, the challenger was fitted with 3.31 axles, the standard fitment when you buy the 5.0-liter V8 engine.

Try not to see this as a two-step ratio difference because each engine is paired with a different standard axle that's best-suited to its horsepower and torque delivery characteristics. Instead, it's best to describe our 2.7-liter EcoBoost has having a "plus one" axle ratio, in that it is one step (of 5 percent) away from its standard offering.

Here's another thing to bear in mind as we go forward: our 2.7-liter V6 crew cab 4x4 with its optional "plus one" axles can tow 8,100 pounds while the 5.0 V8 4x4 and its mere standard axles can tow 9,000 pounds.

Here, then, are the numbers.

EPA Ratings

2.7-liter EB 4x4: 20 mpg combined (18 city/23 highway)

5.0-liter V8 4x4: 17 mpg combined (15 city/21 highway)

EPA ratings are a weighted average that considers all available axle ratios that can be paired with a given engine. The ratings are not adjusted to reflect which one is physically present.

Overall Results after 692 miles

2.7-liter EB: 19.5 mpg (0.5 mpg below EPA combined)

5.0-liter V8: 19.3 mpg (2.3 mpg above EPA combined)

In the end it was a virtual tie. But the 5.0-liter V8 is the clear victor if you compare each to its respective EPA ratings. The V8 was not supposed to do as well, and yet it did.

But our total mileage skews the driving mix toward highway. EPA combined may not be the best reference point to use here. So let's look at each loop individually.

Evaluation Loop - 114-mile mix of city, freeway and two-lane mountain roads

2.7-liter EB: 19.6 mpg (0.4 mpg below EPA combined)

5.0-liter V8: 19.2 mpg (2.2 mpg above EPA combined)

Another virtual tie on our standard evaluation loop, which is nominally 115.6 miles long. But we drove 114 miles here because of a slight construction detour both trucks were required to take.



Orange County Loop - 102 miles of suburban city roads, zero freeway

2.7-liter EB: 18.2 mpg (0.2 mpg above EPA city)

5.0-liter V8: 16.9 mpg (1.9 mpg above EPA city)

I call this the One Lap or Orange County loop, and it is either 106.5 miles or 102 miles around. The longer version uses my house as a start/end point if I'm testing an electric car that has to be plugged in order to start off full. The blocks tend to be a little more open than a pure city loop, which is why I call it a suburban city course. There are over a hundred traffic signals along the way, but you never get caught by them all.

Note that we did not use the 2.7-liter EcoBoost's start-stop system here, in part because it wasn't used in the EPA test cycle and also because we find that many folks prefer to switch the blasted thing off. Here the EcoBoost engine did deliver the better outright result, but not by the margin predicted in the ratings. The 5.0-liter V8 exceeded its rating to a greater extent and kept the contest close, in other words.

Bishop Highway Loop - 476 miles of pure highway and open road

2.7-liter EB: 19.8 mpg (3.2 mpg below EPA highway)

5.0-liter V8: 19.9 mpg (1.1 mpg below EPA highway)

This all-highway loop starts and ends at the outskirts of the LA basin beyond the realm of traffic and heads north up highway 395 to a turnaround point in the town of Bishop, California.

On this day we had strong headwinds on the return downhill leg, but at least both trucks had to deal with the same issue to the same degree. Neither one hit their highway number, but the EcoBoost engine's performance was much more disappointing. It shouldn't have been a tie, and yet it was.

Say what you will about the axle ratio issue, but if you were buying a F-150 Lariat SuperCrew 4x4 with one eye on towing you'd probably be considering a choice between the 2.7-liter EcoBoost V6 with 3.73 gears to tow 8,100 pounds versus the 5.0-liter V8 with standard 3.31 gears that can tow 9,000 pounds.

I know which way I'd go if I was given the chance to order this truck all over again. Why wouldn't I buy the 5.0-liter V8 engine that can tow more if it's essentially as efficient in the real world? It's a no-brainer.

Dan Edmunds, Director of Vehicle Testing @ 19,366 miles (at the time)