UPS has been experimenting with Hybrids and "alternative fuels" for a while.
http://green.autoblog.com/2010/04/07/ups-adds-200-more-hybrids-to-fleet-of-20-000-low-emissions-vehi/They have tried the hydraulic Hybrids. Not a lot of info on why they aren't more prevalent. One article claims that part of the problem is powering the electronic gizmos in the car, but I can't believe that would be sincere. A well designed radio should run a couple of days on a 12V battery. A dual battery system with a battery isolator should be perfect. AC might be an issue, but all the other hybrids seem to be able to deal with it. Personally I don't use it.
The latest generation of Hybrids that UPS is experimenting with is apparently Diesel/Electric Hybrids.
I've been running a VW Rabbit (Caddy) Diesel for a while. Hard to beat the 45MPG at the pump, and likes BIODIESEL too. It isn't the cleanest running of vehicles in the world. But, for a 30 year old pickup, it gives the brand new Priuses a run for their money.
There is a small Mahindra pickup that is supposed to be coming to the USA soon. Designed to get about 30 MPG, with some pretty impressive specs including about a 1.4 ton cargo capacity.
http://www.mahindrana.com/http://www.mahindrana.com/pdf/specsheet.pdfIts release has been delayed a few times, but everything appears to be a green light for a release, perhaps next spring.
GM has been making the Sierra/Silverado Hybrid pickup for a while. I believe it is only a gasoline version though with low 20's for fuel efficiency.
VW uses some of the hybrid technology in their "BlueMotion" line including engines that start and stop at stoplights, even with the manual transmission versions, and using regenerative braking to recharge the battery.
The European Golf BlueMotion gets 50 MPG (US) City, 69 MPG (US) HWY. Hard to beat that, except that one can't actually buy it here in the USA.
VW likely going to introduce a full hybrid diesel shortly.
But, unfortunately, their pickups and small delivery vehicles are lagging behind, especially in the USA.
Peugeot is likely to also have Diesel Hybrid cars available (in Europe) in 2011.