Text: Vince Pornelos / Photos: Vince Pornelos | posted June 17, 2013 14:16
Just to get it out of the way, I'm really not a big fan of being fuel efficient. Whenever it comes to testing a new cars, I just prefer to drive normally and realistically rather than go all out to set fuel eco records. When it comes to fuel eco runs, the thought of waking up the wee hours of the morning, driving long distances all the way into the hottest part of the day with the A/C at minimum (or switched off entirely) all to set fuel eco records aren't exactly what you could call the appealing parts of the job.
That's not to say that I don't find it important; quite the opposite really.
Back in college, all it took me to get to school and back was about PhP 100 worth (about USD 2., more or less) of fuel on my 1300cc Mitsubishi Lancer EL. Mind you, back then my hundred was able to get me a little over 5 liters of unleaded. Today, try filling up with a hundred and you'd be lucky to get two liters. Prices are as astronomical today for each and every one of us than ever before, and it's only going to get higher as supplies dwindle and the methods to extract that precious black gold from the land (or sea) get even more costly.
As a result fuel efficiency is now the highest priority -worldwide- when it comes to a new car purchase. Car brands are racing (in a way) to deliver cars that have high miles per gallon (mpg), kilometers per liter (km/l) or liters per 100 kilometers (l/100km). It's not just the auto manufacturers that have noticed as the tire companies have made it their top priority too, and at the forefront of this development is Bridgestone and their Ecopia line of tires.
It's not our first outing with Ecopia. Last year,Bridgestone Philippines, under Philippine Allied Enterprises Corporation (PAEC), held the Bridgestone Cup, trio of events aimed at highlighting the capabilities of their new tire lines.
We tried out the Potenza line at the Batangas Racing Circuit and, needless to say, we were thoroughly impressed at the performance offered by the rubber. Afterwards, we then headed on to the Clark International Speedway to try out the new Dueler off-road tires and see what they can do in the mud and muck.
The finale, unusually, was the Ecopia EP100. Installed on several examples of the 1300cc Toyota Vios, our car was actually able to achieve 52.99 kilometers (driver and passenger, light to moderate traffic, no A/C, 60 km/h cruise) to the liter after several laps in Batangas and the drive to Alabang, and we didn't even achieve the best in the competititon.
Ecopia works. Simple as that.
The new Ecopia
Not wanting to sit still while the competition works to improve their own products, Bridgestone developed a new line of Ecopia tires. Bridgestone Asia Pacific invited us to get acquainted with the new tires at the 524,000 square meter Thai Bridgestone Proving Ground outside of Bangkok.
Unlike the EP100 we tried out before, Bridgestone developed different types of Ecopia branded tires to suit different vehicles, thus expanding the customer base for Ecopia.
Succeeding the EP100 is the Ecopia EP150. Suited for smaller cars, the Ecopia is targeted at OEM (Original Equipment Manufacturer) sales, meaning that it will be standard equipment when cars roll off the factory into showrooms and eventually into your garage. Bridgestone Asia Pacific proudly stated that Ecopia EP150 is the standard tire for the all new Toyota Vios, the upcoming Toyota Corolla Altis and the Mitsubishi Attrage/Mirage G4 Sedan... at least for the Thai market. The claim? Bridgestone states that the EP150 delivers 2.5% better fuel economy.
The second tire in the series is the Ecopia EP200. While the EP150 was designed for compact and subcompact customers, the EP200 is suited for compact to midsized cars like the Toyota Corolla and the Toyota Camry; of which several examples were present at the proving ground for testing. What's unique about the EP200 is that the inner sidewall is actually stiffer than the outside wall to aid in straighline stability and economy. Bridgestone claims the EP200 can deliver 8.1% better fuel economy than comparable, conventional tires. We'll test that later.
The last tire is the Ecopia EP850. The EP150 and EP200 may be meant for hatchbacks, sedans and wagons, the EP850 was engineered specifically to offer Ecopia's fuel saving advantages to larger crossovers and SUVs. To test this, Bridgestone Asia Pacific had a selection of Toyota Fortuners mounted with a set of EP850 tires on hand. Bridgestone claims the EP850 can deliver 3.9% better fuel economy than similar tires.
The challenge of Ecopia
Designing and engineering a tire that delivers fuel economy hinges on one key aspect: reducing rolling resistance. That in itself is tricky to improve.
The primary purpose of a tire is to afford the driver grip and traction on the road. Simply put, the more grip, the better for handling and safety. Reducing rolling resistance is at the opposite end of that same spectrum, as it involves reducing the friction between the tires and the road.
It's simple physics and trade-offs. Increasing grip means a tire that is better at cornering, stability and safety, but generally increases rolling resistance and reduces fuel economy. Reducing the rolling resistance increases fuel economy but comes as the cost of grip, stability and safety.
The trick is finding the right balance, as Hisao Ushikubo and Joji Watanabe of Bridgestone Corporation presented to us. The development team of Bridgestone introduced more silica into the rubber compound that makes up Ecopia, effectively reducing rolling resistance by 20% in the EP850, 23.5% in the EP150 and up to 47.2% less in the EP200.
With the rolling resistance coefficient (RRC) reduced, the team then set to work about developing a tread pattern that would restore or even improve on the overall stability, grip and safety of the tire. They engineered different profiles, asymmetrical tread patterns, tread blocks, grooves, asymmetrical profiles and other components to come up with tire models that delivered the fuel efficiency numbers they wanted, the longevity and reliability they needed, as well as the handling performance, stability and safety both wet and dry their customers demand.
Did they deliver the goods? Let's find out.
Where the rubber meets the road
After a long morning of classroom presentations on Ecopia, it was time to try out the tires at the Thai Bridgestone Proving Ground itself. However, just as we were about to get started with the drive proper, the clouds unleashed a veritable monsoon in a matter of minutes, prompting us to take a break to let the weather settle down.
With the monsoon paving the way for a lighter drizzle, we then headed back out to get some seat time in the Ecopia-shod Toyotas. The track may have been engineered to produce simulated rainshowers at certain areas (i.e. the skidpad and wet-handling circuit), but today everything is a wet-handling exercise. For the day, the dry-handling exercises were effectively, putting the new tires to the ultimate anti-hydroplaning test.
First we tried out a pair of Toyota Corollas; first with a standard tire and the second run with the Bridgestone Ecopia EP200 on what was designed to be a dry-handling course the multi-purpose test pad. The rain has picked up again in a big way just as I let the car off the line; the long morning in the lecture hall made many of us quite eager to get behind the wheel.
The standard tire performed well, but there was quite a bit of roll; this was not a Potenza test after all. Under braking, the front end gets a little unsure of itself while the back end seemed eager to kick out, but we were pushing the tires to their limits.
With a lap done, I then moved on to the Ecopia EP200 shod Corolla and let her rip. A lap of a short handling course is never really enough to get a full feel for the improvements, so I lined up again and again. I was actually more eager to get a feel for how the stiffer inner wall would affect handling, as I haven't heard or driven on a tire that has an asymmetric sidewall before (to my knowledge). After about 4 runs in the EP200, what was clear was that braking stability is significantly better and initial turn-in was also a bit more positive.
The EP200 car also performed emergency lane changes better and did it with a bit more confidence and composure. It's not black and white, but the differences were quite noticeable the more laps I did in the car.
With the handling portion done, we then moved on to the skidpad to test the limits of the tires on constant cornering. The weather was still having its way with us, but still the Proving Ground staff had the sprinklers on for the skidpad test.
In the standard Corolla, the speedo needle could only do about 55-58 km/h of constant cornering before exhibiting understeer (as evidenced by tire squeal). I actually wish they had a VBOX fitted so we can see the a digital read out of the actual speed as verified by GPS, but we'll have to make do with the speedometer and its inherent error for now.
When we switched to the EP200 Corolla, the difference was clearer than it was on the handling course. Under consistent cornering on a constantly waterlogged skidpad , the limits of the EP200 were clearly higher, able to do 60-64 km/h without tire squeal. Try driving above it and you'll get understeer htat the standard control tire exhibited at around 60 km/h.
Just when we were about to try out the EP850 on the Toyota Fortuners, nature once again took charge, unleashing the second monsoon -plus winds- of the day. With daylight running out, we just had to call it a day.
One thing you'll notice is that we didn't get a chance to actually try out the rolling resistance of the new tires. Bridgestone actually had a driving demonstration wherein three cars side-by-side would pop the transmission to neutral to see how much farther the EP200 would roll down, but it had to be scrapped because of the horrendous weather. I guess we'll just have to postpone the test of the new Ecopia's RRC and fuel economy later on in a more intensive local test. Ditto for the larger EP850.
Nevertheless, from our drive of the new EP200 (for some odd reason, the EP150 was absent in the test cars at the Proving Ground), we know the new Ecopia can perform better when it comes to handling and with far less rolling resistance than before. The new Bridgestone Ecopia line is quite promising but as for fuel economy improvements, we'll put it to the test at a later date.
The automotive world has changed. Fuel consumption was just a byproduct of engineering; just another question a prospective client asked on the showroom floor. Today, it is one of the most important, often defining whether a sale is made or not.
As the new Bridgestone Ecopia goes to show, the tire is as huge a part of overall driving efficiency as the highest pressure direct injection systems, the most high tech valve timing technologies, the most sophisticated variable turbochargers or the most friction-free hybrid drive systems car manufacturers are developing for a market that has had its priorities changed.
The tire, after all, is where the rubber meets the road.