Urban density isn’t the best solution. The greater the density, the greater the pressure for resources in a city (especially water), and the more fragile and dependent on imports it is.

For a much better solution, look at medium-sized cities in the developing countries. The places are mostly walkable, have everything one needs in small to medium shops spread around, have rural areas in the vicinities that can support the place entirely, so thay’re resilient to situations just like this one, with oil prices going up. Medium cities like that could be close to each other, with the populations fairly spread in medium-sized clusteres. That are many more benefits, like much less losses in energy transmission and in the food chain, but it would require a too long text to say it all

Dense cities might look like less from oil, but they need a constant input of resources from far far away, being more dependent on oil and exposed to global instabilities than people think.