2005.5 Jetta TDI automatic initial review

I took a very extended test drive with the new Jetta TDI sedan. Because I do not own the car yet, I will keep the review short and to the point. By the way, the other reviews on this car pretty much nail the issues right on the head. Read the other reviews for detailed information. This review is about the TDI engine, drive train and fuel economy.

I drove the version with the 6 speed automatic. The very first thing I noticed is that the TDI sounds like a diesel, what a surprise! The sound is well insulated from the interior though, and I suspect passengers in the car would not notice that it is diesel powered. The 100HP TDI engine is underpowered for a car this heavy. The only saving grace is that the typical diesel torque is available at low RPM's and allow the car to easily keep up with city traffic without any difficulty. But ask the car to accelerate faster than typical traffic and you will find that there is not all that much more to be had. Top speed is quite high, at an computer limited 115MPH.


The super smooth 6 speed automatic is made by Aisin (spelling?) in Japan and seems perfectly mated to the diesel. Diesel engines have a fairly short torque curve, so the 6 well spaced gears work magic, keeping the engine right at the proper RPM all the time. That is A big plus with such an underpowered engine. It has a manual shift mode that allows easy direct selection of the gears, even if you choose a gear that is higher than what it would normally pick. That is another nice feature, as you can select 6th gear at low speeds for better economy when the conditions are right. There is also an sport mode that holds somewhat higher RPM's for better performance. I used the digital readout to determine fuel economy in the various transmission modes. There is no question that shifting the transmission into 6th as soon as possible results in slightly better economy than in auto mode.

This automatic is so well matched to the diesel engine that the EPA ratings of 35/42 nearly match the manual ratings of 36/43. As I mentioned earlier, I believe you can manually shift the automatic and match the fuel economy of the manual jetta TDI. Interestingly enough, both the manual and automatic have nearly identical final calculated drive ratio's (2.51 manual, 2.53 auto). This means that the no matter which trans you choose, the engine RPM will be almost exactly the same on the highway in top gear.

I was able to achieve an indicated 44MPG at a steady 74 MPH. This translated into an average of about 40MPG including some stop and go driving. Very impressive indeed considering the weight and size of the car. While this does not exactly match the Toyota Prius, there are certain advantages to the turbodiesel, especially at altitude, where no performance is lost due to the turbo.

I do know that older Jetta TDI (same engine) owners regularly exceed the EPA ratings. If that is the case, maybe this car will match the economy of the Prius.

As much as I hate to mention this, there are performance modifications for the TDI that improve power output drastically. Many owners do this after the warranty expires. Some even report slighty better fuel economy!