Friday, October 26, 2012

VW Jetta TDI Performance & Economy Upgrades - Part II

In our last post, we started trying to establish a baseline fuel economy reading on a new stock 2012 VW Jetta 2.0L TDI Sedan with the DSG transmission.  The first half of a 200 mile weekend road trip took us from an elevation of 2941 feet above sea level in St. George Utah to about 6400 ft. elevation in Ely Nevada.  The result was just a shade over 36 miles per gallon.

On our return trip, we started out with 479 miles on the odometer and a full tank of gas. (We did have to put a few dollars of gas in to top off the tank.)   The temperature in Ely was around 65 degrees Fahrenheit when we left back to St. George on August 12th.  Just like before, we drove right at the speed limit or over by 1-3 miles an hour.  We drove "normally" not focused on getting the best economy possible, but not pushing the vehicle at all either.  Getting back to St. George that afternoon the temperature was about 98 degrees.

When we went to the gas station in St. George the next day (thus explaining the extra 3 miles vs. the trip to Ely of only 217 miles) and filled the tank up, the odometer had reached 699 miles, for a total driven of 220 miles.  Again, this was almost all from highway miles at about 65-75 miles per hour.


The receipt below shows that we used 5.326 gallons of diesel fuel.

With 220 miles driven on 5.326 gallons of diesel, our trip mpg average came out to 41.30.  Obviously an improvement over the 36.03 mpg we got on the uphill trip.  The difference, in our opinion, was probably mostly attributable to driving uphill on the way there verses going downhill on the way back.

We decided to figure out a combined trip mpg average.  437 total miles traveled (217 going, 220 coming) with 11.348 gallons of diesel used (6.022 going + 5.326 returning) equates to a trip average of 38.50 mpg.  Not too shabby for a brand new diesel.

Now that we had an unscientific but usable baseline mpg figure, it was time to start bolting on some aftermarket diesel performance parts and then measuring the difference these made. First up, an AFE cold air intake kit.  Join us on our next blog post as we share some photos from that installation.

Wednesday, October 24, 2012

VW Jetta TDI Performance & Economy Upgrades

"What fuel economy gains can I expect from this upgrade on my diesel?"  That's a question we hear many times every day, so we've decided to do some rudimentary tests for some of our most popular aftermarket diesel performance parts and report the results back to you via this blog.  

Let's start by looking at a 2012 VW Jetta 2.0L TDI Sedan with an automatic transmission.  Our test car is basically brand new, with less than 250 miles on it.  The first thing we wanted to do is establish a baseline mileage reading on the bone stock vehicle.  To do this we used a trip of approximately 217 miles from St. George Utah (elevation 2941) to Ely Nevada (elevation 6427).  On August 9th 2012, we filled the fuel tank and took a picture of the odometer.

With 244 miles on the odometer, we hit the road with a full tank of diesel with no additives.  Temperature that day was about 100 degrees Fahrenheit in southern Utah.  With 3 people and luggage for a weekend trip, we had about 800 pounds in the car.  The drive is mostly in rural, farmland, or even high Great Basin desert terrain, with minimal traffic and only a handful of stops.  The average speed on the trip was about 70-75 mph, and it seemed that if we had kept to about 65-70 mph our rpm's would have been in a better fuel economy "sweet spot."  However, we just wanted to get where we were going, so mileage wasn't worried about - we just went the speed limit, or maybe a little over. 

After getting to central Nevada, we refilled the tank.

The odometer was now showing 461 miles.  

The receipt from our fill up in Ely showed that we had used 6.022 gallons of diesel.

So the math works like this; 461 miles on the odometer minus 244 miles on the odometer at the start of the trip equals 217 miles traveled on 6.022 gallons of diesel fuel.  Dividing 217 miles by 6.022 gives us a final trip average of 36.03 miles per gallon.

Since this trip takes you up over 3000 feet in elevation we were interested to see what fuel mileage it would get on the return trip with lots of downhill stretches of road.  We're also curious to see what effect "breaking in the engine" over the next year will have on fuel economy.  

Join us for our next blog post where we show you the numbers from our return "downhill" trip with the stock Jetta TDI sedan at the end of the weekend drive.  Thank you.  And don't forget to shop Parleys Diesel Performance for all your VW TDI performance needs.