Gear changes to improve city milage

[CitySipper]

I have a 2011 Jetta TDI, and while driving around the City, I am getting about 26 MPG. Which I would like to improve because Diesel is about $4.20 where I live.

Looking around the internet, I saw the 5TH gear swap that increases MPG for Highway drivers, and looking around some more I saw cars in Europe that had gears better suited for City drivers, especially the VW Polo. My Jetta has a final gear ratio of 3.45, with stock tires, and was wondering if dropping from 3.45 to 3.39 gear ratio would improve the city's MPG.

I know that lowering the ratio kills top speed, but I almost never get onto the Highway, so I am not concerned about the top speed of the car as long as I am able to do about 50 MPH.

I will look at my numbers once I get under the car, but I was hoping to put the gears from the 2012 VW polo into it.

The Polo's gears :
1th gear ratio: 3,78:1
2th gear ratio: 2,12:1
3th gear ratio: 1,27:1
4th gear ratio: 0,87:1
5th gear ratio: 0,66:1
6th gear ratio: -
7th gear ratio: -
8th gear ratio: -
9th gear ratio: -
Reverse gear ratio: 3,60:1
Final drive: 3,39:1
RPM at 120 km/h (theoretical): 2.400 rpm

And since there is no 5th gear in the Polo, I was just going to keep the stock gear from the Jetta.

 

[Max Period]

How did you shift your gears? Cruising at high rpm + low speeds + low gear increases fuel consumption.

 

[VeeDubTDI]

The cost to change the gear will not pay for itself in fuel savings.

Practicing more efficient driving techniques (coasting, using your brakes as little as possible, etc.) is free and will have more of an impact on your fuel economy than changing the gear ratios.

I recommend studying this thread and the videos included in it: http://forums.tdiclub.com/showthread.php?t=335035

 

[Ski in NC]

Changing gear ratio can help on highway for the older cars, as there is no 6th to pop into for highway cruising.

It does nothing for the city. In the city, you can control the ratio with that stick in your right hand. Plenty of choices available.

Your mpg in true city driving may not be that bad, if it is truly all stop and go.

Best thing is to avoid charging up on lights and then hard braking. Anytime you brake hard, you just wasted a bunch of energy.

 

[GoFaster]

The 5th-gear ratio swap is only viable on the 5-speed-manual cars because in those transmissions, 5th gear can be accessed without removing the transmission from the car, so it is a reasonably easy DIY swap (as long as you don't bugger something up in the process - which certainly has happened ...)

The same cannot be said of the 6-speed manual transmission, which is a completely different internal design.

You can't swap a 5-speed gearset into the 6-speed transmission - because the internal design of the two transmissions is different.

Did you know ... Your 6-speed transmission has TWO DIFFERENT final drive ratios? The transmission has two separate layshafts inside it which each operate a separate final drive pinion. It uses one final drive ratio for 1st through 4th and the other one for 5th and 6th.

That feature also means that there are limitations to what final drive ratios can be selected, because the different pinion sizes mean different center distances between the diff and the two layshafts, and the tooth counts have to work out properly with the center distances of the shafts.

In short ... forget about it.

Besides, normally in city traffic, the road speeds are too low to use top gear anyhow. Making top gear taller will just make it even less feasible to use it.

 

[PressEnter[]]

I'm not sure I get the concept. The problem with city driving is the time spent idling at lights and waiting for other traffic to get up to get moving, not the gearing. If you really want a city car, I'd recommend a hybrid, or maybe one of those micro cars like the new Mitsubishi Mirage.

 

[EuroTuning]

what about adding 6th gear?

http://forums.tdiclub.com/showthread.php?t=346876

 

[03_01_TDI]

City mpg is dependent on the driving style and shifting pattern. Changing gear ratios will not help much if any at all.