EV range and small turbo myths exploded

The results of two recent US studies might surprise electric vehicle naysayers who point to range anxiety and fossil fuellers touting the wonders of downsized turbo petrol engines.

For the electric vehicle (EV) sector, it’s good news, with US analyst Edmunds finding real-world testing on a numbers of EVs yielded a driving range well ahead of official figures from the federal Environment Protection Agency (EPA).

Things aren’t so good for internal combustion engine fans, however. Influential consumer advocacy group Consumer Reports (which correlates to Choice here) has released findings that downsized and turbocharged petrol engines aren’t as fuel-efficient as advocates claim.

Edmunds’ study of nine EVs has shown the EPA to have been exceedingly conservative in calculating an official range figure for all but one of the vehicles tested.

The sole exception is Volkswagen’s Golf blue-e-motion (aka e-Golf), which is still a prototype for which the EPA has not yet ratified a figure. But if the other results are anything to go by, the Golf will come out looking good, too.

Testing took place on a 105 mile (170km) course in suburban Orange County, California. Edmunds says the circuit “includes exactly zero freeway miles, more than a few hills and dozens of signals and stop signs along the way.”

All the requisite controls were in place: same route, same driver setting off at 8.00am into the same weekday traffic conditions. Speed was capped at 50mph (80km/h) in the few places where the limit exceeded that and, because temperature conditions were mild, all cars had their air-conditioning switched off.

For vehicles that didn’t make it back to the start/finish line, the driver stopped testing as soon as possible after the distance-to-empty gauge hit five miles (8km). The cars were then trailered back to Edmunds’ metered Level 2 charge port to get a final, accurate reading on consumption. Those that made it were stopped at the finish line, where supervisors simply added the remaining DTE miles on to the 105 driven for a total range figure.

Edmunds points out this is not a line-honours range competition. What’s important here is the size of the gap between the official EPA rating and the results its own testing yielded in carefully controlled yet real-world driving conditions.

Toyota’s RAV4 EV came out on top with 40 miles left in store at the end of the course, giving it a range of 144.5 miles (232km). That’s a 40 per cent surplus on its official range figure of 103 miles (166km).

The Ford Focus EV’s official single-charge rating is 76 miles (122km), but Edmunds got just under 100 miles (161km) out of it.

Edmunds said BMW’s ActiveE, the Chinese Coda Sedan and Honda Fit (Jazz) EV all made it past the 100-mile mark, enough to put 15-20 per cent on their official EPA ratings.

The Nissan LEAF put in an extra 20 miles over its 73-mile (117km) rating, Mitsubishi’s i-MiEV an extra 14 miles over its 62-mile (100km) official figure.

The EPA was most accurate with the Tesla Model S, with a margin of just four miles over its official 265-mile (420km) range number.

The e-Golf, for which the EPA rating is expected in the near future, made 98.4 miles (158km).

Meanwhile, Consumer Reports has cast its magnifying glass over turbocharged petrol engines, and the results aren’t encouraging for those who advocated the technology as a means of saving fuel.

Its report comes a time when a number of brands including Honda, Hyundai and Kia have been under legal scrutiny for dubious fuel economy claims in the US. Consumer Reports’ investigation of 27 models concluded that, “[generally], the turbocharged cars have slower acceleration and no better fuel economy than the models with bigger, conventional engines.

“Looking at EPA fuel-economy estimates (calculated based on laboratory tests), some of these cars' turbocharged engines seem to have an advantage. But we found those results don't match the findings from our own fuel-economy tests.”

Examples? A 1.4-litre turbo Chevrolet Cruze barely bettered its non-turbo 1.8-litre stablemate in acceleration and delivered no benefit in fuel economy. Indeed, a naturally aspirated 2.0-litre Mazda3 did better.

Ford’s 1.6-litre EcoBoost turbo engine, which comes at a $795 premium over the stock 2.5-litre four in Fusion (aka Mondeo) models, trailed numerous competitors on acceleration, while the overall fuel consumption of 25mpg (9.4L/100km) achieved in testing “places it among the worst of the crop of recently-redesigned family sedans.

“The Toyota Camry, Honda Accord and Nissan Altima, all with conventional 2.4- or 2.5-litre four-cylinder engines, get an additional 2, 5 and 6 mpg respectively. And all accelerate more quickly.”

Particularly relevant Down Under are the results the team achieved with the upspec 2.0-litre EcoBoost engine, which essentially the same as that used in the local Falcon. “[Billed] as having the power of a V6 but delivering the fuel economy of a four-cylinder… our so-equipped Fusion Titanium returned 22 mpg (10.7L/100km).”

This, it continued, “pales against the 25 and 26 mpg we recorded for the best V6 family sedans”, with slower acceleration and less refinement into the bargain.

Even at the costlier end of the spectrum, the team found the value of the downsized turbo formula to be questionable.

BMW’s 2.0-litre turbo four “improved mileage only marginally in the 2013 X3 SUV compared to the six-cylinder 2011 X3 we tested, with essentially identical power and acceleration but somewhat comprised refinement.”

On the upside, it achieved better results with the turbo four-pot 328i living up to improvement claims, with an overall 28mpg (8.4L/100km).

Read the latest news and reviews on your mobile, iPhone or PDA at carsales' mobile site…