[whelmed]

This is my first post here, so hiya all! I'm looking at doing a conversion which will let me get some long-range mileage out of an EV car (need to do a long trip twice a week). So as the guide says, here are some details:

Your skill level with auto mechanics and fabrication: Good with a wrench, am an electrical engineer, but not done any fabrication.
The range you are hoping to get (how many miles/charge): Ideally, 400km
What level of performance you are hoping to get: want to cruise at 110km/h
How much money you are willing to put into your project: 12k GBP
What parts you've already considered, if any: Audi A3 / VW Golf

Based on a few calculations, it would seem that I'll need roughly 24-26kW of power to sustain that speed, or ~90kWh which is 630Ah at 144V. That's given a weight of around 1400kg, a 0.33 CD, 0.035 Rolling Resistance, and a drag area of 2.5m^2.

First thing: I know that's far to much Ah needed, so what I was wondering is if anyone here had experience of coupling EV cars with an electric generator? I've seen a few that can put out 6-10KVA of juice at a low cost, and a few 10-20KVA ones which are quite expensive.

Next: realistically, how much Ah using LiFePo4 can you reasonably stuff into a car? It seems that HiPower has a 144V 200Ah battery rig and according to one of the FAQ's it's only $0.50/Ah (could I get a verification). I'm guessing that it'd weigh about 200kg or so? Any info on this? Would it be crazy to buy two sets of these batteries and run them in parallel?

Finally, are there any other ways that one can extend distance? Are solar panels even worth considering if one lives in Britain?