AZBrandon
07-01-2006, 05:36 PM
In an almost surprise move coming from the most enthusiast oriented mainstream publication (meaning I don't count SCC, Turbo, Import Tuner, etc as mainstream) Larry Webster did an actual scientific testing article for fuel economy tips. It runs as his own column in the front of the August 2006 issue which landed in mailboxes sometime this week for regular subscribers. The five main points were familiar to all of us:
1) Always cruise in top gear
2) Drive slower
3) Turn off the A/C
4) Keep your tires properly inflated
5) Accelerate moderately
The details were as follows. The test car was a new BMW 330i equipped with the 6-speed manual.
Test 1: At 75mph in 4th gear, 26.4mpg. At the same speed in 6th gear, 29.7mpg. Conclusion was to always use top gear, and for automatics, make sure it's in the overdrive capable gear position.
Test 2: At 75mph, 29.7mpg. At 65mph, 33.6mpg. At 55mph, 37.9mpg. He makes the point that if you're going to drive slower than the flow of traffic, STAY in the right lane.
Test 3: He didn't list the exact figures, but he says the BMW lost 5% of it's FE by turning the A/C on when cruising at 75mph, and only 2.5% by putting the windows down. This confirms my own personal testing, and that of many others that it's more efficient on a modern car to put the windows down than it is to use the A/C. This is contrary to popular mythology.
Test 4: The BMW has suggested test pressures of 32 front, 36 rear. Again, at 75mph this yeilded 29.7mpg. Running 10psi low all around dropped it to 28.8mpg. Overinflating by 10psi all around raised it to 30.2mpg. He says "The only downside is that greater tire pressure means a stiffer ride, so you'll have to experiment." He is not among the alarmists that claim higher tire pressures will ruin your tire wear or make your tires explode. Yay!
Test 5: He tested a bunch of different accelleration rates and shifting techniques, such as going flat out to 45mph, which of course results in very low FE for the accelleration but a greater percentage of distance is then cruising at full speed versus very slow accelleration. He claims all his tests will be posted online on their website (http://www.caranddriver.com), but I can't find it anywhere. At any rate, flooring it resulted in just 27.2mpg at the end of the distance traveled versus 30.9 for ultra-slow to 45mph and 30.5 for a modest compromise rate.
Other extras included mentioning that filling up with nitrogen is a waste of money and that it makes more sense just to make sure your tires are always properly inflated. Also mentions extended coasting when approaching a stop helps out since anywhere that you have to use the brakes you're throwing away energy.
None of it was terribly revolutionary or even slightly new to anyone on this board, but for many folks (i.e. their target market) who never even think about FE, this is a very good article that relies on hard data conducted by their technical editor presented very well. It's good to see such a complete, unbiased test published in the front pages of what is supposedly the most read car magazine in the USA.
1) Always cruise in top gear
2) Drive slower
3) Turn off the A/C
4) Keep your tires properly inflated
5) Accelerate moderately
The details were as follows. The test car was a new BMW 330i equipped with the 6-speed manual.
Test 1: At 75mph in 4th gear, 26.4mpg. At the same speed in 6th gear, 29.7mpg. Conclusion was to always use top gear, and for automatics, make sure it's in the overdrive capable gear position.
Test 2: At 75mph, 29.7mpg. At 65mph, 33.6mpg. At 55mph, 37.9mpg. He makes the point that if you're going to drive slower than the flow of traffic, STAY in the right lane.
Test 3: He didn't list the exact figures, but he says the BMW lost 5% of it's FE by turning the A/C on when cruising at 75mph, and only 2.5% by putting the windows down. This confirms my own personal testing, and that of many others that it's more efficient on a modern car to put the windows down than it is to use the A/C. This is contrary to popular mythology.
Test 4: The BMW has suggested test pressures of 32 front, 36 rear. Again, at 75mph this yeilded 29.7mpg. Running 10psi low all around dropped it to 28.8mpg. Overinflating by 10psi all around raised it to 30.2mpg. He says "The only downside is that greater tire pressure means a stiffer ride, so you'll have to experiment." He is not among the alarmists that claim higher tire pressures will ruin your tire wear or make your tires explode. Yay!
Test 5: He tested a bunch of different accelleration rates and shifting techniques, such as going flat out to 45mph, which of course results in very low FE for the accelleration but a greater percentage of distance is then cruising at full speed versus very slow accelleration. He claims all his tests will be posted online on their website (http://www.caranddriver.com), but I can't find it anywhere. At any rate, flooring it resulted in just 27.2mpg at the end of the distance traveled versus 30.9 for ultra-slow to 45mph and 30.5 for a modest compromise rate.
Other extras included mentioning that filling up with nitrogen is a waste of money and that it makes more sense just to make sure your tires are always properly inflated. Also mentions extended coasting when approaching a stop helps out since anywhere that you have to use the brakes you're throwing away energy.
None of it was terribly revolutionary or even slightly new to anyone on this board, but for many folks (i.e. their target market) who never even think about FE, this is a very good article that relies on hard data conducted by their technical editor presented very well. It's good to see such a complete, unbiased test published in the front pages of what is supposedly the most read car magazine in the USA.