Building a jetta for mpg's
 

Hey, I'm rebuilding a '97 jetta tdi, and I would like to get some tips on mods I can do as I rebuild it which will give better mpg's. I'm already employing the driving techniques, but want to ensure optimum fuel economy.
Thanks!
Seth

Hey welcome. If it were me, I'd consider removing the DPF (if it has one) which is illegal here, but it apparently helps MPG. I'd also consider a re-map, as turbocharged cars can benefit with both economy and performance with a few electronic tweaks. As you're rebuilding, think about replacing the injectors, as these can get gunked up over time. Perhaps consider aero mods and switching to a narrower tyre with a lower rolling resistance. Just my thoughts.

I think 1997 was before DPFs. The OEM fuel system might also be biodiesel compatible. Be prepared to replace the fuel filter several times, including road side, if you use biodiesel. There is going to be a lot of gunk built up that it will clean out.

Grill block is a simple mod that helps with aero and warm up times. A belly pan would help with aero, but a front dam is easier to do with much of the benefit. Maybe vortex generators, but these require string testing to get right. Then perhaps flat hubcaps. Any other aerodynamic mods beyond that will involve more work and changes to the car's appearance.

In addition to narrower tires, ones with a larger diameter will also help by making the final drive ratio taller. A lighter wheel and tire set will also help. As for general weight reduction, it comes down to what you are willing to take out and off of the car.

Of course the 1997 Jetta was before the DPF and the fuel system is B100 ready but that wont help your MPG.

• A belly pan will not help your MPG, I have one. It DOES protect your vulnerable oil pan which is useful.
• In the winter if you don't block the grill you MPG will suffer by up to 10 MPG if it gets below freezing. (the farther below zero the more MPG lost)
• The #1 thing you can do is make sure you get a manual transmission! Make sure you buy low rolling resistance tires.
• You can advance your timing a little to pick up a few extra MPGs. I have a 2001 jetta TDI and I advance mine to 70 in VCDS. I notice I get 3-4 MPG more that way.
• chipping the car (remapping) will not help your MPG unless you drive crazy slow.
• Injectors are expensive and likely not very dirty. Use diesel purge to clean them, don't replace. Mine have 330K miles on them and I get 50MPG