Magnifisyncopathological

Charles Maund Volkswagen called me up the other day to make me an offer. I own a 2002 VW Golf TDI GL with less than 63,000 miles on it with an impeccable maintenance record. They are hurtin' for used cars and are doubly hurting for turbo diesels. So they called to offer me a deal: I come in and check out the new 2004 Volkswagen models and they'll appraise my TDI and deduct that amount from the price of a new car. In addition, they'll knock off $1,000 more for being a loyal VW customer.

Realistically, the only cars within my financial reach (and it would be a real stretch) are the '04 Jettas and '04 Golfs. As much as I'd dig a GLI or a R32, I'd have to keep my choices limited to the lower tiers. Regardless of what I'd love to own, what I'd want to own is another diesel. An lo and behold, the TDI engine for 2004 has been upgraded to 100 horsepower (up from 90HP) and 177 foot-pounds of torque (up from 155ft-lbs). Both engines have 1.9 liters of displacement, but the '04 is what's called a Pumpe-Düse. From the VW press release announcing the new 2004 Passat:

Developed in cooperation with Bosch, these unit injectors are located at each cylinder to deliver the fuel for combustion. Because of exacting electronic control, the new Pumpe Düse technology creates a very high fuel pressure and better atomizes and precisely meters the fuel injection into the cylinders. This results in increased engine efficiency and power, with the desired benefits of quieter engine operation, and highly optimized fuel economy.

It is not so much a "change", it's more like an entirely different engine that coincidentally happens to have the same bore and stroke and a few minor bits and pieces coincidentally happen to be the same. The P-D fuel injection system forces many, many other things to be different. Everything in the fuel injection system, head, cam, pistons, rods, everything involved in the timing belt and accessory drives since there is no longer a separate injector pump, etc.

The North American 100hp P-D has different emissions equipment. It's different enough that I strongly suspect that not only are the ECU's different, but that they are incompatible.

The North American 100hp engine has servo-operated EGR (the others are the old vacuum operated design), servo-operated "anti-shudder" valve (instead of solenoid/vacuum), a sensor on the turbo VNT mechanism, and a sensor (we think it's O2 sensor) at the catalyst.

Each engine cylinder is allocated a Unit Injector (UI) which is installed directly in the cylinder head and driven directly through a tappet or indirectly via a rocker from the overhead camshaft. The ECU with map-based control triggers the high-speed injector in the UI. Fuel is injected as long as the solenoid valve is closed. This means that the valve's closing point defines the start of injection, and the length of time it is closed defines the injected fuel quantity.

Across the complete engine control map, Unit Injector Systems permit precise fuel injection with variable duration of injection. The resulting rate-of-discharge curve and the high injection pressure result in efficient combustion. In other words, high power outputs, better fuel economy, and lower exhaust-gas and noise emissions.

Idle and acceleration "diesel clatter" noise is markedly reduced on the PD engine when compared to mine. Vibration is noticeably weaker overall. The power band was wider, allowing for greater acceleration across more RPMs. Peak power is available 100 RPM sooner. For the most part, TDIs just don't smoke that much unless you fiercely stomp on the Go Pedal or mod it for power, such as with a chip or bigger injectors. I noticed zero smoke during my test run...and this was on a car sitting on the lot for who knows how long under moderate to hard acceleration for most of it's run. Essentially, unless someone knows what "TDI" stands for or can smell the exhaust, your passengers aren't going to know you're burning diesel towards your destination. The test drive was very pleasant.

You get standard an AM/FM, tape, CD player in-dash receiver as opposed to the 2002's standard AM/FM tape deck.

Those are the highlights. This new engine and model year isn't without some things that bother me.

One drawback is the fuel economy has dropped from a stellar advertised range of 42mpg (city) and 49mpg (highway) to 38mpg (city) and 46mpg (highway). These are EPA figures, so take them with a few bags of salt. I don't measure my mileage, but I normally get 520-540 miles per tank (almost all moderate to hard driving in a 50% city/highway mix) and the tank holds 14.5 gallons. You figure filling up at 12.5 once the fuel idiot light beams up, and you've got 41.6 to 43.2 miles per gallon. On longer road trips, I've gotten more like 580-610 miles to the gallon, resulting in 46.4 to 48.8 mpg. These numbers are with no performance mods or tire/suspension changes. You can get better mileage. WAY better mileage.

Another beef I've got is VW isn't offering the TDI in a 2-door version. Lame, very lame. I like the slicker, simpler look of the 2-door over the 4-door. It also makes it an event for my friends to ride with me. :)

The new HVAC vents don't adjust up and down as easily as the older ones.

The dealer offered to take my 2002 for $8000. On top of the grand they're offering for my VW loyalty, the total cost for a 2004 4-door, white, 5-speed manual Golf TDI that'll take 6 weeks to get here is $8,775.

Not interested, but thanks for the test drive!