I have one of those. You'd be welcome to borrow it if you'd like to evaluate it.
The GUI is a bit fiddly until you get the hang of it, but nothing like as fiddly as lugging a full sized scope down to the car, finding a way of powering it, looking at it once your head is buried in the engine bay, etc...
I'd say it will do anything you need on a car. The bandwidth is good up to a couple of MHz where the analogue input stages start to give up the ghost. It won't go up anywhere near where the 72MS/s sampling rate suggests it might, but it will be fine for automotive use.
The signal generator bit is pretty useless in the standard firmware. The sine wave looks like it's constructed from a look up table with about 20 values in it!
Alternative firmware apparently improves this and extends functionality to incorporate making tea, doing the washing up and so on. I've never got round to flashing it with anything but what it came with.
I bought mine from Martin Lynch in Staines for around £100 ish (got a small discount during a visit with the anoraks radio club - list price is £129.95) if you want to save the pain of international shipping, customs fees and the usual royal mail extort. They have a demo one in the store you can play with too.