[enragedcacti]

> The batteries are just weight on the highway

Weight is only relevant to acceleration (which is partially recovered), hills (partially recovered), and rolling resistance which is only ~5% of energy usage. Even with a consistent load on the highway the batteries can help by removing parasitic loads on the engine like alternators, a/c compressors, and power steering pumps. Depending on torque demand and specifics of the engine/transmission, thrashing the battery could also be more efficient than ICE alone.

I'm sure there's stuff I've missed, but I think those are the main reasons why a number of hybrids have highway EPA ratings 10-15 mpg higher than the highest MPG ICE car ever produced.

[thsksbd]

"but I think those are the main reasons why a number of hybrids have highway EPA ratings 10-15 mpg higher than the highest MPG ICE car ever produced."

I agree with everything you said, except for this. Is this really true? The Geo Metro is rated 53 mpg highway. The 80s VW diesels had good mpg too.

[enragedcacti]

you're totally right, I mixed up my facts. they are 10-15 mpg higher than the highest MPG ice car currently produced for the US market which is the Mitsubishi mirage.