Jay,

I must say I appreciate your article on how to save gas.  I was especially surprised to see that Engine Braking could actually increase gas mileage as my father always yells at me about my heel-toe down-shifting as I'm coming up to a stoplight.  He swears up and down that shifting the car into neutral and then braking to a stop will gain you better mileage.  That being said, ever since reading your article, I've tried engine braking more often and I've definitely noticed an increase in mileage.  I drive an 04.5 Jetta GLI and it has the "MFA" (Multi-function readout) between the gauges, one feature of which displays your average mpg as well as current mpg.  When engine braking, sometimes I will see my average mpg go up by as much as .2 depending on how long ago I reset the display.  Overall I've been getting up to 1mpg more, as long as I can keep my foot out of the gas! (Yeah right, try driving a chipped 1.8T and see if you can keep from flooring it!) Either way, great tips and keep up the good work. 

Luke Gagainis

Glenview, IL

2004.5 Jetta GLI 1.8T, 14.3@97mph

One thing that I don’t mention is that DFCO has rpm limits. Meaning below a certain rpm, to prevent stall or prepare for you to get back on the gas, DFCO is disabled. So the higher the rpm you coast to a stop the more DFCO you utilize.

Also, using your vaccume/boost gauge is actually the best way to monitor fuel economy cause boost typically uses richer A/F. Stay under boost when you don’t need it and you will save more gas. Watch how much vacuum you pull in different decel conditions. Different gears will pull different vacuum under certain conditions. Most people ask why mpg changes so much. The problem is that mpg takes in the distance or rate you are traveling at too. Under transient conditions like decel, it will not be accurate. If you drive just by the vacuum gauge and try to conserve gas, then on the average you are saving and getting higher mpg.

Just understand that engine braking puts slight wear on the engine, but heel toe wears on the clutch and syncros depending on how good you are at it. In the end, pads and turning rotors is cheaper than yanking a clutch.