Comment by Kon-Peki | Hacker News Reader

Comment by Kon-Peki | Hacker News Reader

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Excellent questions. It was a there-and-back trip, so every foot of elevation lost was also re-climbed (about 100 feet overall - the midwest is pretty flat).

This car has Audi's "energy recuperation system", which is actually a "mild hybrid" system but you'll never see those words on the website or Monroney or any advertising - "mild hybrid" has a terrible public reputation despite the fact that it works (but doesn't have much of an effect on the EPA test cycle). Almost every single Audi (and Volvo) sold in the US has this system. It is also the base model, so the tires and wheels are the base 18-inchers which weigh a LOT less than the 20+ inch wheels that everyone loves (and kill fuel economy). The transmission gear ratios are perfectly matched for the speeds I choose. I use high-quality gasoline from Costco, etc.

Go read other people on Audiworld or other forums. I'm not an outlier. These modern turbo engines are great for highway cruising, but drink fuel like it's free if you want "spirited driving".

As far as I can tell, you won't see "hybrid" on Audi's site because the "energy recuperation system" isn't a hybrid system at all -- it simply banks energy from the alternator and then reduces the load on the alternator (and the load on the engine, as a byproduct) when requested, allowing the car's energy needs to be drawn off the battery during that time instead.

From Audi's literature:

>While the vehicle is coasting or braking, the alternator voltage is raised above the level of the basic electrical system. During these phases the alternator can convert the vehicle’s kinetic energy into electrical energy, which is stored temporarily in the vehicle battery. When the vehicle subsequently accelerates or is driven at constant speeds, this energy is used to relieve the load on the alternator, allowing a fuel saving of up to 3%, depending on the driving cycle.

I am fully aware of how efficient a modern turbo engine can be, and perhaps you did, in fact, best the EPA estimates. Did you calculate these numbers yourself, or rely on the onboard computer?

I keep track of everything myself.

That's fine, we don't have to call it a mild hybrid. But whatever you want to call it, it's working really well on my car. It only has about 7k miles on it, but the efficiency keeps getting better as it breaks-in. I have to imagine that this is probably as good as it will get.

Let me ask you something, though: if I went back and edited the original post to say 30 mpg, would you agree that how someone drives makes a huge difference in their fuel costs. Because that was my main point :)

Yes - I'm certainly being pedantic. You're correct in that driving style can have a huge impact on fuel consumption. You don't have to hypermile it; just not playing speed racer between red lights, cruising at 70 instead of 85 helps, etc.

I was just kind of blown away by the claim. Not that long ago, high 30's MPG on the highway was the domain of economy cars (think Corolla's and the like) and euro diesel cars. To hear that a gasoline SUV, albeit a smaller one, could be close to 40MPG on the highway made me skeptical and curious of how it was achieved.

Many new Audis also have a newer version of Quattro (marketed as Ultra) that mechanically disengages the rear drivetrain.

My A6 wagon gets about 10mpg on the highway better than my in-laws Outback, and I assume this was a large portion of the reason.

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