(so that's what happens on a 50th post...you become an 'active enthusiast'... )
Don't think that's the Accord, Jason...although I couldn't tell you which car that does apply to (and if I could, I'm in the wrong line of work... )
I can confirm what erickbecky says -
*Without the Navi upgrade, you will have no instantaneous FE capability built into the car*
That being said...
Can you *get* a tool that will show instantaneous ? Yes. Get a ScanGauge - about $150, and you'll have access to about 20 data items *besides* instantaneous.
"Can I get an aftermarket Navi system ?"
Sure. Either handheld (like Garmin, et al), or, have someone put a custom head unit in one of the 2 open DIN sized slots underneath the standard HVAC / audio stack. All depends on price you want to pay.
"Can I get both of those for less than the $2000.00 upgrade cost of the OEM unit ?" Sure.
"Will it look nicer ?" That's subjective. Most people probably prefer a totally integrated look, but there's something to be said for giving that up in favor of better performance at (potentially) lower cost.
"Will I recoup the investment if I get it ?"
Judging by the cost of the option, and using the traditional residual value on Accords, I'd say about 60% in the first 3 years, less after that.
"Will I be able to haggle on price on a car with it ?"
No. The HAHs that are selling fast are the ones *with* Navi. Just about full MSRP on those, if you find one. The ones *without* can get an 'ok' all the way to 'great' discount, depending on what area of the country you buy from, and if you're willing to take a car off the dealer's lot (the longer it's been sitting, the better the deal you'll be able to negotiate).
Hope that helps. And I'll confirm what Tink said - I've never seen anyone who got it say they wished they hadn't - but the inverse is certainly true. Nothing to obsess over, though. The important thing is that you're going hybrid, with all the resultant benefits to both you and us. And whatever car gets you there is a good thing, and not to be discounted.
All the best,