The Hunger of Time by Damien Broderick & Rory Barnes
It's an expanded (and apparently more grown-up) version of their earlier title "Stuck in Fast Forward". You've mentioned a few plot points, I'd like to take up the last one.
In the book, the family have just travelled 200-odd years into the future and landed in their garage, right in front of a partially squashed Rolls Royce. As they're inspecting their new/familiar surroundings, Grace (the Mom) notices something strange...
Very calmly, Grace said, ‘Hugh, look at what’s happening to that car.’
Hugh misunderstood. ‘Darling, it was damaged when the vacuole came
into phase with the normative four-space continuum. The fractal
surface of the expanding constriction pressed against the—’
‘I know all that,’ Mom said, not batting an eyelid. ‘Have another look
at the car.’
We all took a closer look. We all jumped back. We all gasped
‘It’s melting,’ Grace said.
The bodywork, the heavy steel wheels and rubber tires, the
undercarriage slumped, sagging like softened toffee dropped on a hot
plate. My own jaw sagged. I held out my hand tentatively, but no
excess heat was coming off the collapsing car...
Hugh believes he knows what's happenning, so when Grace asks him...
‘Well, I can’t be certain, darling, but I suspect that this is due to
nanotechnology. The vehicle is being broken down to its constituents
at the molecular level.’
Need more info? You can preview the book here, here or on this page :-)