Friday, September 18 2009: MPG
>Would like to see what the flogger has to say about this:
> http://www.nytimes.com/2009/09/13/automobiles/13MILEAGE.html
A little known fact: I do requests. I don't have many comments, really. Most of the tips in this article are old news for TDIClub regulars (down to the suggestion about driving as if an egg were under the accelerator), and are all sound advice. At least 75% of fuel economy is psychology. I use the same tactics almost everyday - including catching up to the BMWs and Lexuses that weave and bob to blow by traffic as soon as the road opens up to be multi-lane. The Rabbit has been out of commission lately and I'm getting 41-42MPG in a manual transmission Toyota Tercel by doing "constant velocity" driving. Those fancy low-rolling resistance tires, though, are total shit in the rain or if you do any kind of spirited cornering. Unless the newer brands are any better than the Michelin Energy low rolling resistance tires, I'd recommend staying away from them if you like your tires to actually remain in contact with the road.
What this article really highlights (in my opinion) is just how far VW has come with this newest generation of TDIs. The engine I have in my Jetta is code AHU and was Volkswagen's first electronically controlled direct inject diesel engine. The AHU and its twin the 1Z was basically the same 1.9L diesel VW had been making for 10 years, with a bigger turbo and an electronically controlled fuel pump (and the 1.9L was tweaked from the ultra-reliable 1.6L diesel that VW had been making since late 70s). The AHU and 1Z were followed up by the ALH which more or less provided the same capabilities. The externals were redesigned so it would mount in the new chassis and there were minor tweaks to reduce smoking. All of these engines were phenomenal in their day in terms of the power, economy, and emissions they eeked out of a reliable (basically, 25 year old) diesel engine design. These reliable engines were followed up by the BEW engine which was available from 2004-2007 and used the fancy "Pump-Duese" injection system. These engines were a bit of a disappointment because they actually offered poorer power and fuel economy in the trade-off for improved tailpipe emissions. VW technically took a break for a year and didn't sell any TDIs in North America in 2008 (but amazingly there was an incredible overstock of 2007 TDIs). Then diesels made a return to North America in 2009 with the CBEA engine which uses common rail fuel injection technology to return simply stunning numbers for both fuel economy and emissions. They blow away the stats for all the previous generations of TDI, including the old (beloved) AHU TDI I own.
Not to tweak too many flog readers, but I also think this article pulls back the curtain a bit on the gasoline-electric hybrid wizard, as well. Hybrids rarely achieve these levels of real world fuel economy when highway driving is involved, and still burn a fossil fuel to go. Modern diesels will routinely give you 60+ MPG, Euro-3 compliant levels of tailpipe emissions, and will run on a completely renewable fuel: biodiesel. I think it is truly awesome. My only regret is that I can't get that awesome TDI engine in a simple, no frills VW. VW doesn't do simple and no frills anymore.
> http://www.nytimes.com/2009/09/13/automobiles/13MILEAGE.html
A little known fact: I do requests. I don't have many comments, really. Most of the tips in this article are old news for TDIClub regulars (down to the suggestion about driving as if an egg were under the accelerator), and are all sound advice. At least 75% of fuel economy is psychology. I use the same tactics almost everyday - including catching up to the BMWs and Lexuses that weave and bob to blow by traffic as soon as the road opens up to be multi-lane. The Rabbit has been out of commission lately and I'm getting 41-42MPG in a manual transmission Toyota Tercel by doing "constant velocity" driving. Those fancy low-rolling resistance tires, though, are total shit in the rain or if you do any kind of spirited cornering. Unless the newer brands are any better than the Michelin Energy low rolling resistance tires, I'd recommend staying away from them if you like your tires to actually remain in contact with the road.
What this article really highlights (in my opinion) is just how far VW has come with this newest generation of TDIs. The engine I have in my Jetta is code AHU and was Volkswagen's first electronically controlled direct inject diesel engine. The AHU and its twin the 1Z was basically the same 1.9L diesel VW had been making for 10 years, with a bigger turbo and an electronically controlled fuel pump (and the 1.9L was tweaked from the ultra-reliable 1.6L diesel that VW had been making since late 70s). The AHU and 1Z were followed up by the ALH which more or less provided the same capabilities. The externals were redesigned so it would mount in the new chassis and there were minor tweaks to reduce smoking. All of these engines were phenomenal in their day in terms of the power, economy, and emissions they eeked out of a reliable (basically, 25 year old) diesel engine design. These reliable engines were followed up by the BEW engine which was available from 2004-2007 and used the fancy "Pump-Duese" injection system. These engines were a bit of a disappointment because they actually offered poorer power and fuel economy in the trade-off for improved tailpipe emissions. VW technically took a break for a year and didn't sell any TDIs in North America in 2008 (but amazingly there was an incredible overstock of 2007 TDIs). Then diesels made a return to North America in 2009 with the CBEA engine which uses common rail fuel injection technology to return simply stunning numbers for both fuel economy and emissions. They blow away the stats for all the previous generations of TDI, including the old (beloved) AHU TDI I own.
Not to tweak too many flog readers, but I also think this article pulls back the curtain a bit on the gasoline-electric hybrid wizard, as well. Hybrids rarely achieve these levels of real world fuel economy when highway driving is involved, and still burn a fossil fuel to go. Modern diesels will routinely give you 60+ MPG, Euro-3 compliant levels of tailpipe emissions, and will run on a completely renewable fuel: biodiesel. I think it is truly awesome. My only regret is that I can't get that awesome TDI engine in a simple, no frills VW. VW doesn't do simple and no frills anymore.
Steve wrote:
Do you cut the ignition at red lights? I only did it once, when I was crawling to a gas station on fumes. I heard the Car Talk guys say that idling uses almost no fuel. Seems it would be hard on the starter, and then more fuel is consumed later to top off the battery, right?
Also, what do you think of engine braking? I do it a lot in traffic to save the trouble of putting in the clutch. Does the higher revving alone cause much consumption?