2010 Porsche Carrera-35mpg

[brucey]

I've seen 32 highway mpg out of a LS6 C6 Corvette, automatic transmission no less.

[Big Dave]

It is an article of faith tha good driving is the most effective eco-mod.

Corvettes with 427 engines can get into the 30s. I'm thinking a GTO with a six-speed could give nearly the same results and you would not have to feel helpless on the highway.

Engine displacement is highly over-rated as a parameter to increase MPG.

[basslover911]

The thing is that with such big displacement they have to be geared VERY low, not something every manufacturer is doing.

If they were! Well, imagine going down the road at 1,200rpms (since there is torque for it!)... wow... nice!

[roflwaffle]

Originally Posted by Big Dave

Engine displacement is highly over-rated as a parameter to increase MPG.

It should be engine displacement and gearing. The problem w/ some of the 5+L engines is that they just can't spin slowly enough in a fairly efficient glider to get decent mileage. Course, the cylinder deactivation tech changes all this, so a 5.3L 300-350hp GM engine could effectively be a 2.65L, and w/ a T56 (.5 sixth) and a low enough rear end could see ~70-90mpg cruising at ~60-65mph. Ya know what would be a blast, an El Camino w/ a sloping bed cover and other aero mods as well as LRR tires and the above setup. Toss in a couple beefy electric motors w/ some high power lithium packs at ~80whp/120wftlbs each and right there we've got a ~450whp/550wftlb vehicle that would be a bit porky at ~3500lbs, but would also provide great mileage and blow the doors off of just about anything that moved on the street.

[Big Dave]

The El Camino idea has merit because the El Camino has a lot of dead space in which to put the hybrid circuitry. Good straightforward vehicle to work on. Lots of stuff available.

[roflwaffle]

You know what would be even better for someone economy minded, a 4WD Subaru Brat or a Dodge Rampage (the Omni was 4WD so parts should bolt up). Just drop a 2wd setup in there, make a couple cross members for the electric motors, shorten the halfshafts, and use ~4.5-5:1 reduction for the motors so they'll redline at ~60mph. It wouldn't be quite as fast, but being ~600-800lbs lighter w/ a ton of torque would insure it would still be quick. And in one case, a Rampage w/ a 2.2L turbododge swap, it may even be faster.

[extragoode]

Originally Posted by basslover911

Well, imagine going down the road at 1,200rpms (since there is torque for it!)... wow... nice!

I regularly run my V6 around town in 5th gear doing 25mph at 1k rpms. It doesn't have any problem doing 20 mph in top gear, I just wish I had more gears! 3k@70mph!

I drove my cousins Trans Am with a LS1 engine and the 6spd manual once and was idling along at 20-25mph in 6th around 800rpm. It didn't flinch.