BMW X6 vs Cayenne GTS on Nurgburing test

[shenard]

Originally Posted by Suzie's Dad

BMWs have always had optimistic speedometers, although being accurate at 100 MPH is new to me. Their consumption figures are usually pretty accurate as they measure fuel usage from the amounts that get injected -- obviously the computer knows that number very precisely -- and their odometers are generally much more accurate than their speedometers.

'Chipping' the turbo'd engines will make the computer MPG readings inaccurate as the ECU is fooled into injecting more fuel than it thinks it is doing. So you will get optimistic MPG readings if you go that route.

I have to agree that the on board computer is pretty accurate. So far my last two tanks have been as follows: first tank = on board computer was 12.0 while actual logged as miles divided by purchased fuel was 11.8 and second tank was on board computer = 11.9 while actual logged was 11.678.

I am sure there is a little human error depending on whether or not the fuel lever stopped at exactly the same point both times so I tend to think the on board computer may be a little more accurate

[xDrive50i]

Originally Posted by shenard

I have to agree that the on board computer is pretty accurate. So far my last two tanks have been as follows: first tank = on board computer was 12.0 while actual logged as miles divided by purchased fuel was 11.8 and second tank was on board computer = 11.9 while actual logged was 11.678.

I am sure there is a little human error depending on whether or not the fuel lever stopped at exactly the same point both times so I tend to think the on board computer may be a little more accurate

I agree. Depending on the amount of pressure buildup during re-filling the tank (I'm talking about the gas tank here not the X6 ), the pump may trigger prematurely and cuts the fuel off. Unless you fill up the tank to the point where the gas is actually overflowing, there is NO guarantee that the tank is always filled up to the exact same point. This can also vary from pump to pump.

The other point I like to make is that people are saying that the on-board computer may not be accurate enough. Well, the on-board computer knows exactly how much gas was used and exactly how far you traveled. So based on these two factors, I would argue that the on-board computer is by far the most accurate. If people use the 'fill up at the pump' technique by dividing the miles or kilometers they traveled (which the on-board computer provides!) by the gallons or liters they put into the tank AND you consider what I pointed out above, I think it shows that this technique can't be as accurate. You may get close, but I highly doubt you get it as close to the REAL consumption as the on-board computer does!