I have a 2010 1.4, 8v Punto Evo, She had been sat for a few days ( using my Seicento :slayer and had previously run to and from work flawlessly ( 12 miles there and back, mostly motorway ). We had decided to go out for a Sunday run, and just as I had got to 70mph on the motorway there was a horrible shake that could be felt through the steering and peddles, couldn't make my mind up at the time if it was a severe misfire of wheel balance issue, also a couple of times the car dipped as if it had gone into a hollow in the road ( seemed to be from the driver side rear, as if a damper had failed ) , so aborted trip and headed for home, Monday went to get all four wheels balanced wheels, took her out for a run and the vibration seemed to occur at 60-65mph but was nowhere near as bad, but I still had a couple of occasions where the back end seemed to dip out briefly, like a gust of wind had caught the car, the day after I took her to the mechanic where I go for my MOTs to get him to check the steering and suspension etc, everything was secure with no obvious signs of wear, he swapped the front wheels with the back and said to give it a run ( that was Friday, not open over the weekend ) so give her a run over weekend and problem still exists, was intending on his advice to get wheel balancing re checked, but can't get that done till tomorrow now, would appreciate any advice if anyone has had a similar problem, initially I was just going to get mechanic to chuck a new pair of rear dampers on, but when he'd had a look he said all seemed fine, no signs of leakage etc, any idea's ??