30 years ago Porsche was planning to build a low emission sportscar. With a wind slippery body (cw 0.25) and a low not too wide body, combined with a 4 cylinder 2 liter engine it would have been fast enough with less than 10 seconds from 0-100 km/h (yes this was still fairly fast in 1980) and a 200+ km/h top speed. And thanks to the low weight of less than 800 kg Porsche calculated a (ECE standard) fuel consumption of less than 4.8 l/100 km. Even today, this would be quite impressive.
Well, we know, Porsche never produced this car. And to be fair, it's pretty probable that it wouldn't have been a sales success. But what I am really wondering is that if they thought a 4.8 l/100 km sportscar was possible in 1980 why on earth can't we build a 2-3 l/100 km sportscar today? I am totally convinced that all it takes is available! And, differently to the good old days, it might be well possible that people actually would buy the car. Look at the Smart Coupé, people actually did like it and it sold, even if it didn't meet the volume expectations of Mercedes.