Recumbent/lay-back is the most efficient and comfortable
"The innovators tried and tested almost any conceivable rider position and again the recumbent position emerged as the preferable posture, both for pure speed and for practical and comfortable road bicycles/vehicles. Soon human powered vehicle (HPV) became almost synonymous to recumbent bicycle. HPV is now a specialist term, while recumbent bicycle is much better known." Yang peliknya belum sampai kepada kereta Solar. Mungkin di sebabkan oleh undang undang kereta tapi aku belum terbaca. Dari buku percuma: https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=8fc53e68afeee2a50f0a7477485c744cb5529636