"...the Prius is the most fuel efficient vehicle at each speed point from 1 mph to 100+ mph compared to any other car on the market."
I'd suggest this is untrue.
A 1998 VW Passat TDI will do over 800 miles to a tank of diesel in the UK. Or cruising at 70mph on the motorway you can easily achieve 50-60 MPG.
I appreciate that fuel in the UK is of a higher quality then in the USA, so the figures will be off. Also our gallons and of a different size.
But still, these Priuses do not seem any more efficient, even here in the UK.
I do not understand why they don't make a diesel/electric hybrid vehicle, surely that would be a perfect mix?