Just filled up with HPR near Elk Grove earlier today while doing some Pick-n-Pull parts shopping.
Definitely has a small increase in power/response. Does absolutely smoke less. I've got oversized injectors on loan in my B4 sedan at the moment and they do smoke no matter what. The difference is noticeable. I've only got 80 miles on the tank so far. No telling what the difference in Fuel economy will be until I've run the complete tank through. Mileage up until this point hasn't been great lately, though. Usually stuck in traffic, hauling a lot more weight than the average driver both in terms of heavy tools and hauling people, often times at the same time.
I used to run B20 regularly in my old Mk3 about 10 years ago. But since I did go on long trips back then, I would have to switch between regular diesel (most states were just transitioning to ULSD at the time) and B20 at my usual haunts in Michigan. The pump inevitably started leaking.
In the meantime as someone who wrenches a lot of TDIs, I have noticed a number of common issues on biodiesel. The way the seals swell on biodiesel is very uneven. And in fact they swell too much, in my opinion. In California, most of our biodiesel uses waste vegetable oil as a basestock. I've definitely seen a number of cars run regularly on the stuff have some nasty varnish-like build up inside the fuel system.
I purchased a 2005 Passat wagon a couple years ago for cheap, only had 80k miles on it, because the owner ran it on B100 almost exclusively. I have a stack of receipts totalling the amount of around $15,000 in repairs, many of which were to address a "vibration" issue from the engine. Injectors were replaced, balance shaft module changed to the gear driven unit, new cam and followers, new OEM axles, engine mounts, transmission, new injectors, new injector harness.
The real problem? The injectors (again). The openings for fuel inlet on the PD injectors are quite small and clog up fairly easily on sub-par fuel. To make matters worse, PDs basically cook the fuel before it even gets to injectors. Conventional biodiesel could often times break down before getting to the injectors in these engines. I replaced the injectors again in the car and it took care of the issue. While I was there, there was definitely a notable brown varnish in the passageways in the head that feed the injectors.
I've seen too many issues and oddities happen from running biodiesel, especially California biodiesel. The stuff I had in the Mid West was made from virgin soybean oil, that stuff was decidedly better.
Either way, my experimentation with that particular form of renewable diesel ended. Once I resealed my first injection pump on my own TDI back in 2006, I decided to keep things simple for my daily driver and reduce the amount of issues, I would keep running it on regular diesel from then on.
I've told many customers that I personally like the concept behind biodiesel, but the product itself tends to be sub-par. This new HPR stuff, on the other hand, has my attention. The end product seems a lot like the "synthetic" diesels out there that likely utilize the Fischer-Tropsch process of turning gas to liquid. The gas can be anything from natural gas to a gassified biomass. Very high quality, clean and super high cetane. And also much closer to the type of fuel manufacturers designed their engines for in the first place. Conventional biodiesel, not so much...
So, for those of you with issues having leaking pumps, that's the same issue you'd have switching to ULSD from bio. This confirms to me that chemically, HPR is more similar to conventional diesel. This is something I personally would prefer, as the seal swelling I've seen from re-sealing a number of biodiesel running injection pumps, is not natural. The chemical reactions caused by conventional biodiesel is not doing your fuel system internals any favors. And again, ULSD is what manufacturers designed the engines for in the first place. You want a renewable fuel that's going to give you fewer issues than biodiesel will and also allow you to seamlessly switch to ULSD when necessary? Here it is. HPR.
No washing down of cylinder walls causing fuel dilution of engine oil. No unnatural over-swelling of seals. No coking injector nozzles, no coking injector inlets on PDs or varnish. No issues with soot and ash loading in commonrail DPFs. In fact, from the lower amount of smoke I've seen out of the back of my B4 with oversized injectors, there should be less regens necessary on a DPF-equipped commonrail due to the smaller amount of soot created in the first place.
This is the type of renewable I personally have been waiting for.
