I think it's worth $0 - low $xx to another domainer not in the know.
A website is not vital to a cab company, unless it's an innovative company planning on making apps (GPS locator, estimated wait times, etc), you may see something like that down the line in a few years in NYC first, not so much in Indy, I've lived there a couple of years and am from NYC, there's not nearly the amount of hustle and bustle to warrant those type of investments/technology there just yet.
A domain is only valuable if it has end users that understand its value. You could offer Flowers.com to a little Mom and Pop flower shop in a small town in Nebraska for $1000 and they would say "They'd get back to you" - A big idea needs a big budget, that budget isn't there for an Indianapolis cab stand.
If you're going to invest in the new 1 word gTLDs, I think it may only be wise if every other major extension is taken for the keyword + extension.
Example:
CarInsurance.com, .net, .org, .info, etc, all taken = Car.insurance worth it.
TaxPro.com, .net, .org, info, etc all taken = Tax.pro worth it
LuxuryEstates.com, .net, .org, .info etc, all taken = Luxury.Estates worth it.
IndianapolisCab.com is taken, but .net, org, .info, etc have never been registered before = No demand.
IndianapolisCabs.com is available for regfee, I think you'd have a better chance selling that one.
G'luck