This is a bit of an old story that I had largely forgotten about. Was just having a conversation with someone that brought the memories back up. While it’s fresh in the memory, I figured I’d share.

It was 10 years ago (2009) and I was living in Michigan, working in Ann Arbor at a tire shop where I was the wheel alignment and suspension technician, which also happens to be where the EPA is headquartered, conveniently located not far at all from the headquarters of the major American automakers and many of their suppliers and production facilities.

The car in question was an early 2000s Ford Expedition with a very odd, prototype drivetrain. It was a diesel hydraulic hybrid. It gets dropped off, and I get the key to it, not knowing anything about it, and I get in it and immediately notice the stench of what smells like automatic transmission fluid. The instrument cluster is also a completely custom made unit and there are various extra switches and a large emergency shut off button.


We had to call the guys who dropped it off to figure out how to get the thing going. Turns out the one guy removed a piece that would make it so it couldn’t start, to which the other EPA employee said “Well, they DO have to drive it to do this job, what were you thinking??”

Electronic gadget re-affixed, I get in and drive it into the shop. Once underneath giving the suspension an inspection, I saw why it smelled like ATF. It was a hydraulic hybrid. Two massive accumulators filled what used to be open space under the passenger compartment and both axles had hydraulic motors driving them directly and some of the hand-made connections were leaking slightly, so they had zip tied some automotive diapers underneath to catch most of the leaking fluid.

Now I get to the diesel part. The internal combustion engine doesn’t always run, the vehicle gets up and moves under hydraulic power and as hydraulic pressure depletes, the little diesel engine comes on and revs up to resupply hydraulic pressure. But the moment the diesel started, it sounded strangely familiar to me. I had been driving a 1998 VW Jetta with a 1.9 TDI diesel in it since 2004, and it was originally my dad’s car he bought new in 1998. So, I had to pop the hood to confirm my suspicions. Sure enough, it was a 1.9L ALH code 1.9L TDI engine (my mk3 Jetta was an older AHU code with a different block design, but largely the same operating principles and same style fuel system).

So, I do the alignment and go for the mandatory post-alignment test drive to make sure the wheel is straight it isn’t pulling. Most bizarre driving experience ever. It’s not all that unusual to operate, but the noises it makes are insane. This fairly loud whirr from the hydraulic motors as you get moving, then suddenly this angry little 4 cylinder diesel comes to life and revs up to replenish the hydraulics, it just sounded like the loudest, most pissed off chainsaw ever. It was the oddest sound.


It wasn’t horribly fast, but I later figured out what the reason for this prototype was. This was not to be the only time I encountered this odd vehicle.

Several months later, one of my friends who was sub-leasing an outbuilding where we stored and worked on some VW and Mercedes diesels on the side said he got a call from the EPA. Apparently the EPA had been talking to IDParts, a vendor of many TDI engine parts and performance upgrades. Apparently the EPA wanted to consult with us on a few ideas to get more power out of the little 90 hp diesel lump on recommendation from IDParts.


So, an appointment was setup and we call got to drive to the EPA’s headquarters in Ann Arbor, drive through the secured gate with special guest pass we had been given, walk through metal detectors and the whole deal that is SOP with most federally-owned facilities. Walked down a couple long hallways that seemed like they were nothing but dyno room after dyno room and was even showed a prototype UPS truck using a similar hydraulic hybrid drivetrain for testing.

Eventually we get to a large, open shop space where the same red Ford Expedition was at, with the hood open, and we’d discuss what injectors, turbos and other upgrades would be needed to nearly double the output of the little diesel. Took a peek at the timing belt and told them that would likely need attention soon as it looked like one of the older, 60,000 mile rated belts and had some signs of aging on it, the representative said their technicians should be able to handle it no problem. We were also showed that the original VW instrument cluster was still tied into the system with immobilizer reader coil and RFID chip from one of the donor vehicle’s original keys. They put them all in a black box and stuffed it under the hood somewhere. It is possible to remove the immobilizer on these without too much hassle, but the EPA didn’t have the tools or know-how for such hacking.


The other interesting tidbit from the EPA rep was that the Expedition was constructed as a demonstration for officials to drive something they might already be used to driving, get a feel for the differences between their normal drivetrain and this odd setup. It seems most of their hydraulic hybrid research at that point was aimed more towards frequent stop and go delivery trucks for companies like UPS, and obviously that’s not a vehicle the average person gets to drive, so they made the Ford to have the same concept, but downsized to operate a more average style vehicle.

And that was all. We had our nice little tour and discussion with the EPA rep and got showed their interesting work and were never contacted again and I never saw the prototype again either. Somewhat anti-climactic, but it was an interesting experience to say the least. I do now wonder what that setup actually got for fuel efficiency. Those numbers were not disclosed.


Sadly, I don’t have any photos of this oddball, but it did make a couple stops on the auto show circuit for a few years, including the Washington D.C. auto show where another friend of my Michigan group tried to convince them to bring it to the then annual TDIFest that was being setup to be held over Labor day weekend at a Dulles hotel that year. They declined. Instead, we got a couple TDI Cup racing drivers with their race cars and the then new V6 TDI Touareg to show up.

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