If fuel consumption is your only consideration the first gen can't be beaten.
If you like having a rear bench and want good value for money and reliability the second gen is worth a look. They can be had fairly cheap now.
On a fair day with a delicate right foot up to 70 mpg is possible in the second gen.
The CVT has a very wide 'gear' range, allowing you to pootle along at 1100 RPM @ 35 mph or just under 2000 RPM at 60 mph.
Revs that low defeat the need to P&G for economy.
Yes you can get better economy in a manual first gen - but unless you really put effort in it, not by that much. See my log and the hybrid fleet list.
I won't claim being objective, after all I own one
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2011 Honda Insight + HID, LEDs, tiny PV panel, extra brake pad return springs, neutral wheel alignment, 44/42 PSI (air), PHEV light (inop), tightened wheel nut.
lifetime FE over 0.2 Gmeter or 0.13 Mmile.
For confirmation go to people just like you.
For education go to people unlike yourself.