As well, that price differential also accounts that the A6 TDI is a V6 being compared with a lowly four-cylinder gas engine (Mercedes-Benz E and GLK Class diesels are cheaper than their V6 gasoline counterparts because they’re four-bangers). To be sure, some of that margin includes some non-powertrain upgrades (as well, I’m guessing, for some healthy profits for Audi). In this case, Audi asks for a whopping $9,800 more for the base TDI than the 2.0T. The biggest detriment to the diesel, at least in this case, is the premium charged for the compression-ignition engine. At idle, the diesel is a little noisier but that’s more apparent to passersby than occupants.
There is much more low-end torque (though the little four-banger is no slouch in this arena), passing power is more convincing and it feels just as smooth at speed. On top of its obvious fuel advantage, the 3.0 TDI was also more enjoyable to drive than the 2.0T. The diesel, by contrast, was almost spot on its rated consumption: 8.5 L/100 km in the city and 5.3 on the highway. It is worth noting that the 2.0T actually bettered its Natural Resources Canada rated fuel economy (10.5 L/100 km in the city and 6.8 on the highway), the first time a gasoline-fueled car has accomplished that in our testing. At the end of our cruise through the scenic little burg of Port Hope, Ont., the TDI’s digital fuel economy readout displayed 8.3 L/100 km while the 2.0T was indicating 9.5, the margin in town a slightly smaller 15%. We thought that the 2.0 might get back a little of its own during our short city drive, but here again, the turbodiesel proved surprisingly frugal. If the decline in efficiency is accompanied by the vehicle pulling to one side, the brake system should be inspected immediately.This advertisement has not loaded yet, but your article continues below. In addition, any brake issue can make the vehicle dangerous to drive. Stuck Brake Caliper: A stuck caliper on a disc brake or a stuck shoe on a drum brake can lead to a serious decline in gas mileage. Fuel filters need to be replaced periodically. The fuel filter screens out contaminants in the fuel, and over time it will become clogged. If this issue is not addressed it will lead to a rough, idle, sputtering and stalling.Ĭlogged Fuel Filter: A clogged fuel filter will also cause problems with gas mileage. This will lead to a decline in gas mileage. A bad fuel pump can lead to a rough running engine because it is not getting enough fuel. The fuel pump can become clogged or malfunction. The fuel pump pulls fuel from the gas tank to the fuel injectors. Checking the tire pressure and have the alignment checked on regular basis can help prevent this problem.ĭefective Fuel Pump: Fuel delivery issues can drastically affect fuel efficiency. Misaligned Tires: Tires that are low or out of alignment can lead to a drop in fuel efficiency. A dirty airflow sensor will degrade fuel efficiently and lead to a rough idle and even stalling as the problem progresses. It delivers that information to the vehicle's computer, which crunches the numbers and then delivers the proper amount of fuel to the air in the vehicle.
Malfunctioning Mass Airflow Sensor: A mass airflow sensor detects the amount of air coming into the fuel injection system. This can lead to a lack of power as well as a big decline in fuel efficiency. If they are dirty or working incorrectly, it can cause the engine to misfire, leading to poor engine performance. As it progresses, the injectors may have to be replaced.īad or Dirty Spark Plugs: Spark plugs ignite the fuel in the combustion chamber. If caught early, simply cleaning the injectors can solve the problem. This can lead to a drop in fuel efficiency as well as slow acceleration and the car not having enough power. Over time the fuel injector system can become clogged. It can also lead to failed emission tests and a rough idle.ĭirty Fuel Injectors: Fuel injectors spray fuel into the cylinders where it is mixed with air and ignited. If the sensor is dirty or failing it can lead to a drop in miles per gallon. The data is used by the vehicle computer to adjust the amount of fuel entering the engine. Service type Car is getting worse gas mileage Inspectionĭirty Oxygen Sensor: An oxygen sensor measures exactly how rich or lean the exhaust gases are when they leave the combustion chamber.