The funny thing with these long warranties is that people fail to actually realize how expensive they are. If you expect to get something replaced at 99K miles on any GM vehicle, you better have every last service record, and the service has to be performed by a GM dealer, or the warranty is void.
Since they typically charge 50% more than a private shop for the same work on these service intervals, your super warranty is going to cost you an arm and a leg by the time you get to 100K miles.
I'd rather just drive a car I know will do well for me in the long run, and not worry about funneling more and more needless wasted cash into GM's dealer network, in order to have a "warranty" through them.
You should not shift to neutral to coast if your car is an automatic; you won't save any fuel, and could ruin the transmission.
It is illegal for a car manufacturer to require that service be performed at the dealership. All that is required is to keep receipts for all your service. As a mechanic, I do all my own servicing and I have never had Ford, GM or Chrysler raise any objections or refuse warranty repairs. They have to honor the warranty even if you modify the vehicle. That is the law. If any dealership refuses to honor your warranty under these conditions, the BBB or a good lawyer can quickly change their tune.
My Ford Fiesta 1100, which I owned a few years ago, achieved around 42 MPG (converted to American gallons). I never used super-fuels, super-oils, super low resistance tyres, or tactics such as rolling downhill out of gear.
I wonder if we have really gone anywhere in fuel economy terms since the Fiesta was designed in 1976.
Perhaps in America, but in many countries, it's either authorised dealer services/repairs, or warranty is void. It prevents many roadside self-taught mechanics from tampering with something they know nothing about and have no liability for.
No - because with every advancement that makes cars more efficient like fuel injection or variable valve timing, the cars have become heavier as they became much safer, negating the gains of engine efficiency. Cars have also gotten larger. Look at the Mk 1 Golf, which is smaller than today's Polo. I parked my 2001 BMW 316ti hatchback next to a 2013 Kia Rio at the supermarket - and the Rio was a bigger car! In some countries they have 1.6-litre engines; here in NZ they only have a 1.4.