[mpg_numbers_guy]

True. In that case rather than spend the $$ on a whole new drivetrain, you might get an inexpensive first gen Insight - better MPG and maybe more of a "wife-approved" car than the Metro.

The Honda lean burn engines would be great in the Metro - more power and better fuel economy, but seems doubtful that such cross pollination would be possible without some serious modification and time dedication. I'm having a hard time thinking of a more fuel efficient GM produced drivetrain than what came stock with the Metro/Swift.