Which Car Gets the Best Fuel Economy?

A lot can change in one year. We had the idea to bring four frugal, fuel-sipping cars together to determine which was the most fuel-efficient and the cheapest to run, and which did better in specific driving conditions. While the EPA’s fuel economy estimates are a good guide for determining a car’s overall thirst for fuel, we wanted to do our own controlled testing to see how different types of cars performed in the real world.

Indeed, the results of the original Gas Sipper Smackdown were telling, but the cars were hardly the sort most Americans could actually consider buying. The Smart Fortwo was frugal, but it was blown all over the windy desert and it didn’t sip enough to counter its myriad compromises. The Ford Focus was one of the cheapest, most efficient American cars on the market, but it was an unimpressive rehash of a nearly decade-old design. The VW Jetta TDI was a used car and a previous-generation model since no non-luxury diesel car was then on sale. The eventual fuel-sipping winner, the Toyota Prius, was bound for a complete redesign.

Fast-forward to the summer of 2009 and things have really changed. Not only are fuel prices much different (especially diesel), there are more green-oriented vehicles than ever, with even more technologies introduced to get the most miles out of the least amount of fuel. We decided to revisit our cage match of fuel sippers, this time with a new and/or redesigned roster of green players to see how each did in our meticulous fuel economy testing.

We changed the name to Fuel Sipper Smackdown to reflect that diesel isn’t gas and to leave the door open for future smackdowns when other alternative fuel technologies can make it to Las Vegas and back (sorry, no electric cars yet). The goal wasn’t necessarily to determine a winner, but to find out the areas and environments in which each car excels and just how thrifty it really is.

The Cars
The 2010 Toyota Prius is a return player in name only. In reality, the world’s most popular hybrid has been completely redesigned for this model year, delivering new styling, a new interior and most apparently, better fuel economy. Playing copycat is the 2010 Honda Insight, a car whose styling closely apes the Prius but whose hybrid technology is simpler and therefore cheaper. We have compared these two vehicles before, but here is the chance to really put their mileage claims to the test.

The new 2010 Ford Fusion Hybrid not only represents the U.S. of A., but also a segment that was lacking in the original smackdown: a larger, more family-oriented fuel sipper. On the opposite end of the spectrum, the 2009 Mini Cooper represents the small, city-dwelling car as well as one that’s actually fun to drive. Finally, the 2009 Volkswagen Jetta TDI features the latest in “clean diesel” technology available for purchase in all 50 states. It promises the same sort of high mileage as last year’s used diesel Jetta, but without the dirty exhaust.

The Procedure
Under the strict guidance of Vehicle Testing Director Dan Edmunds, each car followed exactly the same test route and testing procedure. Over two days, the five fuel sippers would participate in three driving portions. The first was the back roads portion, or San Bernardino, California, to Las Vegas via the Mojave Desert and Death Valley, which provided a slower speed than the typical highway journey as well as steep grades. The second was a 200-mile city loop, or eight hours of tediously meandering around suburban Las Vegas in search of the area’s many In-N-Out Burgers. The final portion was the highway jaunt from Las Vegas back to San Bernardino on Interstate 15.

Before departure, each vehicle’s tires were filled to manufacturer spec. Every car would be fueled by the same person at every fuel stop to prevent any differences in refueling technique, while each car would return to the same pump in San Bernardino and Las Vegas.

To prevent short fills or other irregularities, we waited several seconds after the pump “clicked off” for the fuel to settle before topping off to the next click. This is particularly important with diesel, which can foam up during filling. We jotted down the needed refueling data — trip computer mileage, gallons used, price per gallon — as well as the onboard fuel mileage readout to test the accuracy of these notoriously inaccurate gauges.

We would drive normally with traffic — no hypermiling, drafting or accelerating like the lead-footed gear heads we normally are. The lone manual transmission car, the Mini, would be shifted in a relaxed manner between 2,500 and 3,500 rpm, while the Prius and Insight would utilize their “Eco” modes designed to maximize fuel economy. Cruise control would be used whenever possible to maintain a consistent speed and eliminate differences in driver technique, although all five drivers would rotate in and out of each car.

The Back Roads
The champ: 2010 Toyota Prius with 47.2 mpg
2nd Place: 2010 Honda Insight with 44.1 mpg
3rd Place: 2009 Volkswagen Jetta TDI with 41.2 mpg
4th Place: 2010 Ford Fusion Hybrid with 39.6 mpg
5th Place: 2009 Mini Cooper with 38.5 mpg

This was the diesel Jetta’s domain last year, but the all-new 2009 model falls back in the pack to a still-impressive 41.2 mpg due to a more powerful turbodiesel engine that did a better job tackling the extended grades through the Mojave and Death Valley. The all-new Prius, on the other hand, maintains its pace to take the first victory. As expected, the Insight came close to the Prius, but its mild-hybrid technology couldn’t match the Toyota’s full-hybrid setup, which features more battery power and a more highly developed ability to run on electricity only.

The bigger Fusion Hybrid showed an emerging trend of not matching its EPA estimates, but 40 mpg from a big, heavy sedan is nevertheless impressive. Similarly, the Mini was last, but its quick handling through the twisting roads into Death Valley proved you can still have fun in a fuel sipper.

The City
The champ: 2010 Toyota Prius with 48.7 mpg
2nd Place: 2010 Honda Insight with 43.4 mpg
3rd Place: 2010 Ford Fusion Hybrid with 35.1 mpg
4th Place: 2009 Volkswagen Jetta TDI with 31.6 mpg
5th Place: 2009 Mini Cooper with 30.1 mpg

As expected, the 2010 Fusion Hybrid moved up in the rankings and the Jetta TDI took a dive during the 200-mile city driving loop through suburban Las Vegas. Indeed, the electricity-boosted powertrains of the Ford, Honda and Toyota are intended to thrive in this sort of environment where frequent slowing and braking plows energy into their batteries for reuse. However, the Fusion’s 35.1 mpg is a far cry from the EPA rating of 41 mpg, while the Prius also fell short of its EPA-rated 51 mpg city.

We obviously didn’t follow the same testing procedures as the EPA, so this provides some evidence for our theory that these next-generation hybrids have been tuned specifically to thrive in the EPA test. The others, on the other hand, beat the EPA ratings.

There was more than just fuel economy revealed in this loop, though. The Insight showed the limitations of its mild-hybrid design, as its air-conditioner does not work when its engine automatically shuts off at stoplights. This happens when the climate control is in Auto and regardless of whether the car’s in Eco mode or not. In a hot city like Las Vegas, this could be a deal breaker, as keeping the air-conditioner blasting would keep the engine running and worsen fuel economy. It’s that or, as we discovered, sweat.

Although the back roads portion was identical to last year’s smackdown, the city route was completely different, so comparisons are not recommended.

The Highway
The champ: 2010 Toyota Prius with 47.4 mpg
2nd Place: 2009 Volkswagen Jetta TDI with 40.6 mpg
3rd Place: 2010 Honda Insight with 38.6 mpg
4th Place: 2010 Ford Fusion Hybrid with 36 mpg
5th Place: 2009 Mini Cooper with 33.3 mpg

All but the Jetta failed to match its EPA equivalents, although our mountainous up-and-down route from Las Vegas to San Bernardino is hardly typical. For instance, the Insight lacked torque from both its battery and gasoline engine to help it up the long stretches of uphill, while its engine didn’t shut off like the Prius and Fusion Hybrid on the equally long downhill stretches. On the other hand, the torquey Jetta was in its element with a turbodiesel engine that thrives over long distances and differing grades.

The Discrepancies
Along the way, we began to notice some discrepancies. For one, the trip meters in each car differed in their mileage totals despite each vehicle traveling exactly the same distance. In total, the difference between the lowest reading (774.4 in the Fusion) versus the highest reading (796.7 in the Jetta) was 22.4 miles. We average out the five different distances when calculating each mpg figure.

Not surprisingly, the onboard fuel economy gauges also differed from reality. While the others ranged from 1 mpg better than reality to 3 mpg worse, the Toyota Prius was woefully inaccurate. On the back-road route, the Prius’ computer claimed it was getting 6.8 mpg (14 percent) better than it actually was, while the city yielded a 5.4-mpg (11 percent) over-report. This sort of shenanigan could mean a higher customer satisfaction score from owners who think they’re getting better mileage than they actually are. This is a shame given the Prius’ actual fuel economy dominance.

The Final Cost
The champ: 2010 Toyota Prius used $45.32 worth of regular gasoline at 47.6 mpg
2nd Place: 2010 Honda Insight used $51.16 worth of regular gasoline at 42.3 mpg
3rd Place: 2009 Volkswagen Jetta TDI used $55.22 worth of diesel at 38.1 mpg
4th Place: 2010 Ford Fusion Hybrid used $57.85 worth of regular gasoline at 37.3 mpg
5th Place: 2009 Mini Cooper used $67.09 worth of premium gasoline at 34.5 mpg

In this category, the price of fuel makes a huge difference. Last year, diesel cost $4.43 per gallon while premium cost $4.17. This meant that despite achieving a better final mpg tally than the Smart, the Jetta was costlier to run. A year later, diesel was $2.66 per gallon — equal to regular in San Bernardino and cheaper in Las Vegas. Certainly, with this sort of comparative pricing, purchasing diesel makes more sense. At the same time, the Mini’s premium fuel requirement raised its total cost by $4.55.

The CO2 Impact
The champ: 2010 Toyota Prius with 0.55 pound of CO2 per mile or 0.214 total tons
2nd Place: 2010 Honda Insight with 0.62 pound per mile or 0.241 total tons
3rd Place: 2010 Ford Fusion Hybrid with 0.70 pound per mile or 0.274 total tons
4th Place: 2009 Volkswagen Jetta TDI with 0.74 pound per mile or 0.289 total tons
5th Place: 2009 Mini Cooper with 0.75 pound per mile or 0.296 total tons

For those purchasing a green car because you’re concerned about limiting your contribution to global warming, this is the section to consider. Obviously, burning less fuel equates to less CO2 pumped into the atmosphere, but gasoline and diesel emit different types and amounts of greenhouse gases (listed here in CO2-equivalent terms), explaining why the Jetta gets a lower score here despite achieving better fuel economy than the Fusion.

The Conclusion
The big news is that the 2010 Toyota Prius (base price $22,000) secures a straight sweep by achieving essentially the same fuel economy regardless of driving environment. Conventional wisdom used to be that the Prius was good for city dwellers and that frequent road trippers should look elsewhere. These results would prove otherwise, and the new Prius proved to be a better long-distance car than before, with a bit more power and a more comfortable cabin.

The 2010 Honda Insight (base price $19,800) is the cheapest hybrid on the market and certainly delivers fuel-sipping savings at the pump as well. However, its mild-hybrid powertrain that creates those savings leads to usability compromises — most notably the air-conditioner shutoff. Also, the Insight’s restricted backseat space makes it significantly less practical than all but the Mini.

The 2009 Volkswagen Jetta TDI ($22,270) proved the promise of clean diesel technology. While not delivering the best gas mileage or the lowest price, the Jetta is better equipped than the hybrids’ base models and feels the most like a normal car. With fewer costly technologies onboard, there are also fewer costly technologies to fix or replace in the long term. Of course, the fluctuating cost of diesel fuel is something to consider.

The 2010 Ford Fusion Hybrid (base price $27,270) was the most expensive car in this test, but it was also the biggest, the most comfortable, the most luxurious and achieves the best safety scores. Among the small group of hybridized family sedans, this is definitely the one to buy. However, it’ll take eight years to recoup the hybrid’s price premium over the regular four-cylinder Fusion with fuel savings.

The 2009 Mini Cooper (base price $18,550) was the least expensive car in the test, but also the least fuel-efficient. Its thirst for premium fuel further hurt its cause. However, the Mini is the fuel-sipping car for driving enthusiasts, and its tiny proportions make parking and maneuvering through busy cities a snap. As one editor said, “If this is fuel sipping, sign me up!”By James Riswick, Automotive Editor

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