there is plenty of information on the wiki under Donor car selection, but basically it boils down to finding the smallest, lightest, most aerodynamic car you can find. If all else fails, look at EPA gas mileage ratings. The more efficient it was as a gas car, the more efficient it will be as an EV. Unless the car got at least 30mpg on gas I would look for something else.
for my money most of the best cars to convert are late 80's to early 90's japanese hatchbacks, sedans and sporty cars.
As for the volvo, few people convert anything that new so I doubt you will find any direct experience. I don't know about newer volvos, but older ones tend to be boxy and heavy. But look for anything similar to what you want to do here: www.austinev.org/evalbum. Maybe somebody else has done a newer model volvo.
There are way too many variables to give you an educated guess as to range without knowing things like how much money you want to spend, what sort of performance parameters you want to see, your minimum required range, your local climate and driving conditions, etc. To get the most out of this forum you need to do some research yourself and learn the lingo and tradeoffs involved in building an EV.
To try and answer your question, Long story short if you were willing to throw a lot of money at it, there is no reason why you could not build a volvo S80 that could do 100 miles (160km) on a charge at freeway speeds. Depending on the size of the trunk you may not even need to sacrifice seating space. The parts are all available off the shelf. But if you are only hoping to spend a couple of thousand dollars to achieve this, forget it. Such a setup would probably cost around $30K (US retail prices for the parts only)
I converted a 1995 Volvo 850, which is basically the same as the S70 through model year 2000. The S80 is larger. You can convert an S80 but you will need a lot of battery to overcome the weight. With lithium, you should be able to hit 50-60 miles of range at a minimum. Also, you probably will want to go with a manual transmission - it is likely difficult to work with a sophisticated automatic.
I will ask what others may be thinking. If you are getting a 2009 Volvo S80 for free, why don't you sell it and buy an older donor car with the money, and use what is left over to pay for the components?
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