That's the bane of the small vehicle. They're dangerous at high speeds because there is no "crush space" to them. With lighter weight should come the active safety bumper (as opposed to the passive safety measures of seat belts and airbags).
It will look and act like this ...
Now this wouldn't work for a full size vehicle. The size, strength and cost of such a device would be prohibitive ... but in a very small auto ... it's all but indispensable. It might be activated by the foot travel on the pedal alone ... or ... simply keyed to foot travel-pressure and engine driven ... possibly hydraulic. In any case, whenever you press the brake pedal, the bumper begins to deploy. And conversely, when you take your foot off the brake ... the bumper returns to its normal position.
In some accidents this would not work and only a seatbelt or airbag would save the occupant but in most cases you have a second or two to get to the brake. When you slam on the brakes the engine should divert power to bumper deployment.To save the occupant from a head-on at 60 mph into a concrete bridge abutment, might require 4 feet of extension. That should be enough. You might not just walk away ... but you should survive. Heck, I remember seeing a 60 year old man belly-flop into 11 inches of water from a height of 40 feet ... it was his "show". And he just got up and walked away ... no problema.
I also believe a break away passenger pod would be useful in keeping down the cost of the device. After all, in a severe collision, we don't care about the vehicle ... just the occupant. Therefore, if pressure sensitive bolts break off under too much strain and release the occupant pod, there will be less mass to stop thereby requiring a less robust gizmo.
In the gas department ...
We're due to run out of petroleum in a few more decades. The cost of gas should go up fast starting in about 10 years. Watch for the armed forces to gobble up whatever they need. Passenger cars will have to go to hydrogen fuel cells (very problematic). It isn't easy to make and liquify hydrogen for common over-the-counter use.
Another option (which isn't even being worked on as far as I know) is ... rotation storage. Store energy in a rotating ring and tap this source electromagnetically. Then, you could gas up your vehicle by simply plugging it into any electrical outlet. No more gas stations. Your fuel tank would have the shape of a sphere since the "full" tank would have to rotate at least once per day with the earth's rotation (like a top or the Fizeau experiment). Lots of problems here ... all solved in the most common UFO design ;o)