Venturabass
Veteran Member
I just thought I'd make this post about a recent test I performed. I've read a lot about obtaining maximum fuel economy by driving at around 55-60mph. So I thought I'd give it a shot, and here are the results...but first a few things...
I have a 2001 VW Jetta TDI with 51,000 miles, 5 speed manual, and the powertrain is completely stock. I use a 15 gallon treatment of Stanadyne Performance Formula everytime I fill up. When I fill up, I do not vent, I simply fill until the fuel line is about 1.5" below the top of the stem, then cap it up. I run my tires at about 42psi up front, 40 in the back. In normal driving conditions I hardly get over 3K rpm in all conditions. Highways I usually drive 75-80mph, city usually 45 regardless of posted limits, traffic pending, and usually in 5th gear when possible. I live in CT, where the summers average 80-90 degrees with pretty good humidity most of the time and few cool days after a cold front has passed through. Elevation is no more than a few 100 feet, I'm right near the ocean. I usually get about 45-46 mpg range. My weekly driving consists of work 15 miles one way (city and highway) and traveling to MA (highway) on the weekend. Lastly, I prefer windows over AC most of the time.
Now, my test had a few specifications.
1. I believed that running the car at 55-60mph whenever possible would acheive the greatest fuel economy because (in 5th gear) the engine sits right around max torque at 1900rpm. Highway driving was considered to be very slow relative to traffic, while city driving was a lot faster than most folks.
2. No A/C use, and no windows unless speeds were low enough around 40mph or so. This was obviously to reduce drag and extra engine work. This sucked.
3. When I was accelerating, try my best to never run the engine at over 2000 rpm. Again this way, to keep it at max torque at all times. Accelerating was therefore very slow, but I'm sure this helped when pulling a cold engine out on the road in town.
THE RESULT:
This took about a week. Driving was mixed city and hwy. I'd say 70% of the miles were hwy, but I also got stuck in some bumper to bumper situations and congested city traffic. Cruise control was used as much as possible, a must in the freeway. I marked up 677.5 miles (633 when the fuel light came on) and the total fill up was 13.134 gallons. That puts me at 51.584mpg for the entire tank. I doubt it was a fluke, as the fuel gage moved much faster around town, and when on long hwy trips, it was apparent that I was getting this kind of mileage.
CONCLUSION:
I've always read stuff about fuel mileage in the 50's on this site and I was always sceptical. I have only gotten to 49.6mpg once in the 25K miles that I've owned this car. I've been in sub-zero temps with a ****ty MAF sensor, getting 35.5mpg on a tank, *in pain*. haha. I now understand with the right operating techniques how to make this engine shine. I can only imagine if these miles were all one continuous highway trip in the spring or fall when temps were cooler! Thanks for reading, and please share any comments!
I have a 2001 VW Jetta TDI with 51,000 miles, 5 speed manual, and the powertrain is completely stock. I use a 15 gallon treatment of Stanadyne Performance Formula everytime I fill up. When I fill up, I do not vent, I simply fill until the fuel line is about 1.5" below the top of the stem, then cap it up. I run my tires at about 42psi up front, 40 in the back. In normal driving conditions I hardly get over 3K rpm in all conditions. Highways I usually drive 75-80mph, city usually 45 regardless of posted limits, traffic pending, and usually in 5th gear when possible. I live in CT, where the summers average 80-90 degrees with pretty good humidity most of the time and few cool days after a cold front has passed through. Elevation is no more than a few 100 feet, I'm right near the ocean. I usually get about 45-46 mpg range. My weekly driving consists of work 15 miles one way (city and highway) and traveling to MA (highway) on the weekend. Lastly, I prefer windows over AC most of the time.
Now, my test had a few specifications.
1. I believed that running the car at 55-60mph whenever possible would acheive the greatest fuel economy because (in 5th gear) the engine sits right around max torque at 1900rpm. Highway driving was considered to be very slow relative to traffic, while city driving was a lot faster than most folks.
2. No A/C use, and no windows unless speeds were low enough around 40mph or so. This was obviously to reduce drag and extra engine work. This sucked.
3. When I was accelerating, try my best to never run the engine at over 2000 rpm. Again this way, to keep it at max torque at all times. Accelerating was therefore very slow, but I'm sure this helped when pulling a cold engine out on the road in town.
THE RESULT:
This took about a week. Driving was mixed city and hwy. I'd say 70% of the miles were hwy, but I also got stuck in some bumper to bumper situations and congested city traffic. Cruise control was used as much as possible, a must in the freeway. I marked up 677.5 miles (633 when the fuel light came on) and the total fill up was 13.134 gallons. That puts me at 51.584mpg for the entire tank. I doubt it was a fluke, as the fuel gage moved much faster around town, and when on long hwy trips, it was apparent that I was getting this kind of mileage.
CONCLUSION:
I've always read stuff about fuel mileage in the 50's on this site and I was always sceptical. I have only gotten to 49.6mpg once in the 25K miles that I've owned this car. I've been in sub-zero temps with a ****ty MAF sensor, getting 35.5mpg on a tank, *in pain*. haha. I now understand with the right operating techniques how to make this engine shine. I can only imagine if these miles were all one continuous highway trip in the spring or fall when temps were cooler! Thanks for reading, and please share any comments!
