I won't hold my breath for a seismic shift in the political landscape. Opinion polls tend to do just that; canvass opinions. They rarely tie in opinions with actual voting intentions. Plenty of people, if asked, "if there was a general election tomorow, who would get your vote?" do plump for the Lib Dems. But the poll analysis shows that a lot of those who now profess to support the Lib Dems are the under 30s and women; and neither of these groups has a great record for actually voting.
Add to that the fact that Clegg has two more television debates (and he's already played his joker insofaras he can't make another remarkable debut for the non-political public) before polling day and that the party's policies are now coming in for serious criticism and scrutiny, and I think we'll see a depressingly familiar political landscape after May 6th.

Quite what stinky old cars (like my ancient Land Rover) have to do with the election debate is beyond me, however.