Hybrid battery status

Hi all,

I have a Gen2 2008 Prius with quite a few miles on it, 155,000 or so... it's nearly 7 years old.
Most of that has been freeway driving at around 70mph. (Motorway here in the UK) A minimum of around 120 miles per day, 5 days a week.

The only fault was a squeaking water pump that I swapped out about 2 years ago.
I've had one set of spark plugs, one 12 volt battery and all of the disk rotors changed. (they rusted badly).

I've had the usual minor scratches etc and one "incident" where a 4 x 4 Mitsubishi Shogun ran in the back of me stuck in traffic on the M4 motorway, new bumper and paint job.

The car has performed beyond my best expectations to be honest.. a pat on the back for the Toyota engineers from me. To be honest I've abused it.. had only one major service and probably 3 oil changes.. ;-)

I recently had a recall (about 8 months ago) on the hybrid coolant pump and the steering shaft.

My next issue will most likely be the main traction battery. I'm using a Scanguage 2, is there any way I can see if the main traction battery is starting to drop in performance? There are no dashboard indications and all seems normal.

I've recently changed jobs, 5 miles to work instead of 55!
My previous freeway MPG (UK gallons) was around 55/58 mpg give or take.. now it's around 49 mpg, it's cold and not really enough time for the ICE to warm up correctly so this drop off is to be expected.

I've never had any issues with any dashboard alarms, although I once had an issue with the MFD (years ago) freezing and not updating - powered off and back on again solved that one and it's never happened again.

Fingers crossed the old girl will keep on running like water down hill!