Impractical? I guess that depends on your personal definition . . . . and maybe where you live - No doubt things are more expensive in California than where I live
My wife and I (family of two) have 5 cars, three iMiEV's, a Ford Transit Connect Van and a Chevy Volt (along with a Sprinter motor home.) Other than one iMiEV, (The 'spare' one bought because it was ridiculously cheap and we LOVE our iMiEV's) all get driven regularly. Practicality (for me at least) is driving the vehicle best suited for the trip you're taking. We each daily drive our own iMiEV so the others don't get used that much. The Volt is used for longer car trips and the van when we need to haul or tow something. No door dings from parking at the grocery store in either of those 
I guess the only downside other than the cost of license plates is car insurance, which runs us right at $100 per month. I feel that is kinda offset by the fact that driving the the iMiEV's most of the time keeps our two more expensive cars (the Volt & the van) 'young' since they only get used for what they're best for. The van is a 2014 and it recently rolled over 30,000 miles and the Volt is a 2017 and only has 25,000 on it. Both of them should easily last us for another 10 or 15 years before they get anywhere near 100K
'Only' three cars for a family of four? I'm guessing a couple of you haven't turned 16 yet? Is there a better, more practical car for a teenager to learn on? I guess there probably are lots of BMW's and Mercedes in the high school parking lots these days, so perhaps I'm more than just a bit out of date?? :lol:
Practical . . . . or impractical? - Guess it depends on your definition, but doing most of your everyday miles in a $5K car, while your $40K or $50k car rests in the garage, only used when you really need it, is a practicality of a completely different sort. More and more communities are legalizing Golf Carts on public streets and that alternative is making lots of cars last much longer - Our 'alternative vehicles' are more practical because they have heat and A/C and some measure of crash protection . . . . plus, we're not limited to 25 or 30 miles per hour
Maybe, it's all in your perspective - I'm sure you do have good reasons why the third car is impractical . . . . but then maybe you're thinking of selling the wrong one?
Don
