[Diesel_Dave]

Congrats on the 60+ mpgs!

My guess is the belly pan would be worth the extra 30-40 lbs. Curb weight of that car is probably over 2,000 lbs so 30 lbs is only a 1.5% increase in weight. Or thinking of it another way, diesel fuel weighs ~7 lbs/gal so 5 gallons of diesel fuel adds another 35 lbs.

Another thing to consider is that you could make one now out of the sheet metal and then later use the sheet metal as a template for the final coroplast one. You might also want to leave portions of the sheet metal one in place for reinforcement. Plus, if you're like me, everything always goes more smooth the second time around. Consider the sheet metal pan a trial run.