ORIGINAL: 1971Chall
RLSH700,
Thanks for the response, you always give me a couple of good things to think about. It will be interesting when the Challenger finally gets it's manual trans. My thought is it will pick up a 1 -2 mph in trap speed over the automatic. The Challenger's 5 spd automatic does have a very steep first gear(3.58) so as far as launch goes I don't think that will hinder it very much. The parasitic loss from the converter and front pump is the real difference between the stick and auto. In the short run(to 60mph) there will be little difference. After that if the driver can shift good the manual should show an edge. I am totally confident the fuel economy will exceed the number we are being given as long as you drive it for economy. Jeremiah, my father has a 2005 Town and Country with the 3.8 and he is getting quite a bit better than what you are experiencing. The mpg meter in the dash is showing 22mpg combined right at the moment. I know on a trip we had last year he was following me back from a car show and got 28mpg(straight highway). I had my '71 Challenger and with the 3.55 gears I kept it at 60mph so that is where he was also. To put this in perspective I just checked out a new Caravan with 3.8. You know what's on the sticker? 16/23 city/highway. This is with the new ratings. That's simply not accurate as my dad has essentially the same thing and I just mentioned what he gets. The new Mustang GT I just bought shows 15/23(ironically the same as the Challenger 5.7 stick) and I will bet my paycheck it's getting a lot better than that on the highway for sure and a little bit better in the city. I haven't taken mpg with it yet but will soon. The new HEMI has a lot going for it. The higher compression and variable cam timing is very efficient at cruise speeds. I wish I had the car right now to test but eventually. My thoughts are 25mpg is not out of the question especially at 60 - 65mph. It's just hard to drive that speed in most urban areas but can be done if you have the patience. RLSH700 makes a couple of good points about the terrain you are driving on. I would have to suspect there are some other factors influencing your results.
You're welcome and thank you as well. I enjoy reading your posts for the same reasons. I know the W5A580 has a short first gear to start off with, that is most likely why the Challenger had the lead to begin with since the overall gearing favors the Challenger in acceleration along with a NA 2 valve per cylinder OHV engine will generally shine in the lower end of things over a 4 valve per cylinder DOHC supercharged engine, my point is I think that the shorter overall gearing with the manual will provide even further starting advantage and I believe that since the gap between the 1st & 2nd gear on the manual will be smaller than the gap found on the 1st & 2nd gear on the automatic, it will be able to maintain this advantage by keeping in the peak range better than the automatic can combined with the greater efficiency in the manual. You are right that a lot will depend on the driver; however, I believe that with the upgrades that this transmission has received, I think less experienced performance drivers (such as myself) will be able to better maximize the benefits over the older T-56 Tremec that the concept had since the magazines pretty much claimed that when Dodge used the upgraded transmission in the Viper, they addressed many of the issues they had been complaining about since the production of the car.
I'm estimating that the fuel economy will be something like 20-21 on the highway for the SRT-8 with the manual under the new ratings since the displacement increased, the compression ratio is slightly lower, no VCT, and the gearing is shorter than the R/Ts. Many times a car's potential fuel economy depends the most on the way the driver drives it over many other factors as well as how they deal with factor