Thursday, December 16, 2010

Fuel consumption: BMW 318i

In this episode the fuel consumption will be treated, not the one that is stated by the manufacturers and is usually too low, but the fuel consumption during regular driving. Please do not derive any definitive statements from our test, the fuel consumption you might have will always co-depend on factors like road condition, tires, your personal driving style and local traffic and weather conditions.


First we start with a BMW 318i Facelift (E90 / MY2010). The car is fitted with a 6-speed manual transmissoion and a 4-cylinder, 1995 cm3 engine with 143hp and weighs 1335 kg. BMW has spend a considerable amount of effort to decrease the fuel consumption of their cars by introducing Efficient Dynamics in an increasing amount of models. 

The Efficient Dynamics package includes:
- Auto start-stop function, that shuts down the engine while the car is in neutral
- Brake energy regeneration, that is collecting energy for your battery, reducing the strain on the engine
- Electric power steering, only activated when turning your steering wheel
- Optimum shift indicator, telling you when to shift up or down in order to maximize fuel efficieny
- Lightweight engineering, reducing the weight of the car
- Reduced rolling resistance tires
- Low-friction fluids
- Active aerodynamics, in order to optimize the aerodynamics of the car

For more information about how the technology works, please visit the BMW website.

But what does this mean for real-life fuel consumption? Lets take a look at the first segment of our trip included driving on several types of roads:

Quiet city traffic (@60km/h = : 10%
Secondary road (@ 90 - 100km/h / 55 - 62mp/h): 50%
Highway (@ 145km/h = 90mph): 50%

BMW states the fuel consumption to be, we found the following results under real-life circumstances, driving a test route of 81,5km (51 miles).



- City traffic (5%): 8,1l / 100km or 29,04 mpg (US) vs. 4,0l / 100km or 58,8 mpg (US)*
- Highway (55%): 5,3l / 100km or 44,38 mpg (US)    vs. 7,0l / 100km or 33,6 mpg (US)
- Combined (40%): 6,3l / 100km 0r 37,34 mpg (US)  vs. 6,3 / 100km or 37,34 mpg (US)**

* during the time of your test drive, little traffic was encountered. Therefore, the results have been substantial lower compared to BMW's result that includes repeated stopping and accelerating, increasing the fuel consumption substantially.
** That our fuel consumption matches BMW's combined figure is based in the fact that our city traffic figure is much lower, during rush hour it would result in a substantial risen combined fuel comsumption.
Please take a moment to see the road and traffic conditions during our test in the video below.


 
Our second result is derived from a couple of days driving in which a distance of 1300km (813) miles has been covered, most of which on the highway. This time we did not try to drive as economically as possible, but had a regular driving style with fast drives on the highway.
 
Our final combined fuel consumption was 8,0l / 100km or 29,4 mpg (US). Taking these results into account, the most likely consumption for average drivers in the BMW 318i will be between 7,0 to 8,0l or 33,6 to 29,4 mpg (US).
 
Next episode:
 
Mercedes Benz E220 CDI Kombi W212

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