For light duty vehicles I always thought that a turbo diesel along with an hydraulic hybrid train would be teh best solution. Redesign the aero dynamic and you can get a pick up that run at 30MPG

Please people! Do save a lot of time and money and look up the Artemis web site about their series hydraulic automobile test or the INNAS NOAX website about their proposed series hybrid or just go back to the work leading to the UPS truck that had a series hybrid automobile in its development. Artemis proved their system on the road in a real vehicle. Bosch is keeping it under wraps now, and Artemis is testing (or tilting at) windmills. Series Hydraulic hybrids have been proven to save fuel, and have been retrofitted to existing automobiles. ..HG..

Seems like this is a good match for stop-and-go traffic (e.g. garbage truck), but won't it be less efficient for cruising down the highway, especially when compared with a modern downsized, turbocharged drive train? How much energy do you lose with a pumped fluid drive train versus direct mechanical connection driving at a steady 65mph?

If we would have put a fraction of the R&D resources spent on HEV/EV on hydraulic hybrids, we would have had them in production already. As this article indicates, this might start to happen now... Whether hydraulic hybrids have greater potential for reducing FC than kinetic hybrids remains to be investigated.

Hydraulic PHEV isn't practical. The energy capacity of hydraulic accumulators is much too small.

I expect everything to go electric in the long term, but hydraulic or air hybrids still make tons of sense in the mean time.

There is no conspiracy to stop hydraulic hybrids and they don't need any research. They exist, are fairly simple and cheap.

They have advantages (price mostly) and disadvantages (efficiency) compared to an HEV with supercaps or a flywheel.

It's very simple, each type can be produced and customers (mostly fleets with city focused vehicles) do a TCO evaluation, takes a bribe from their "favorite" and then writes up an RFP to favor the one who bribed them (or their brother-in-law, etc.)

:-) I wish I was only kidding here.

They all work, which one gets purchased depends more often on the dirty side of the political system.

Healthy Breeze,
You'd be surprised at how little energy it actually takes to stop/start even the largest vehicles in city traffic.

According to the NYT studies done the last couple of years, the average speed of their buses is about 13 mph. Even when they come to a complete stop from say 25mph, a 40,000lb bus only needs about 280Wh of energy storage (after mechanical losses) for regen braking...and then using that same regen to start up again and get mostly back up to speed.

That's only a few kg of Li batteries or maybe 30-40kg of supercaps.

It's just not that much or that expensive considering that city bus costs $400,000+ to start with.

And of course, it's a trade off. If they want to be able to cover speeds with total regen, say up to 60mph (about 1.65kWh), then you start getting a much bigger battery/supercaps/hydraulics/flywheels, whatever. But it's a simple ROI on the additional energy capacity vs the number of times that particular vehicle will actually get up to those speeds on their daily routes and come to a full stop.

Europe may have realized that electrified vehicles will eventually replace all those mechanical contraptions. EU (and many others) may be on the right track.

Yes, HEVs, PHEVs and BEVs seem to put enough pressure on manufacturers to come up with more efficient ICE units. It will not be long for the first 60+/mpg HEV to come to the market.

Since kinetic and hydraulic hybrids show a potential for both better fuel economy and lower cost than electric hybrids, we should not neglect them as some of you propose. Instead, I would be in favor of equal terms when it comes to government funding.

BTW, the first 60+ ICE vehicles have been on the market for quite long. VW Lupo 3L and Audi A2 3L both could do 80 mpg (diesel).

Many of you have not read the literature about the actual Artemis hydraulic hybrid that was built and tested and had at best double the efficiency of the same model car with the same size engine in a standard test. The hydraulic losses were recovered, in all cases, by more efficient running of the engine. A smaller engine would have given even better performance. INNAS NOAX, has several devices to increase hydraulic efficiency, has also an interesting proposal for a electric-hydraulic-hybrid, which I had been keeping secret, now on their website. A cheap battery and a cheap low power electric hydraulic pump for constant operation combined with their hydraulics or engine hydraulics for a much cheaper long range electric hybrid.

Empty air pressure tanks are much cheaper than super capacitors and their electronics for the same power density which is why a UPS company uses air tanks and a turbine to keep their cheap small flywheel going until engines can start. Hydraulic hybrids avoid the cost and complexity of high-power electronics. ..HG..