There is a good breakdown of the CPI on the US BLS Site:
https://www.bls.gov/charts/consumer-price-index/consumer-pri...
Highlights that explain the overall 4.2% jump:
* Used cars and trucks 21.0%
* Gasoline (all types) 49.6%
* Airline fare 9.6%
https://www.bls.gov/charts/consumer-price-index/consumer-pri...
Highlights that explain the overall 4.2% jump:
* Used cars and trucks 21.0%
* Gasoline (all types) 49.6%
* Airline fare 9.6%
Table A. Percent changes in CPI for All Urban Consumers (CPI-U): U.S. city average
Seasonally adjusted changes from
preceding month
Un-
adjusted
12-mos.
Oct. Nov. Dec. Jan. Feb. Mar. Apr. ended
2020 2020 2020 2021 2021 2021 2021 Apr.
2021
All items.................. .1 .2 .2 .3 .4 .6 .8 4.2
Food...................... .2 .0 .3 .1 .2 .1 .4 2.4
Food at home............. .1 -.2 .3 -.1 .3 .1 .4 1.2
Food away from home (1).. .3 .1 .4 .3 .1 .1 .3 3.8
Energy.................... .6 .7 2.6 3.5 3.9 5.0 -.1 25.1
Energy commodities....... .7 .5 5.1 7.3 6.6 8.9 -1.4 47.9
Gasoline (all types).... .7 .5 5.2 7.4 6.4 9.1 -1.4 49.6
Fuel oil (1)............ .7 3.3 10.2 5.4 9.9 3.2 -3.2 37.3
Energy services.......... .5 .9 .2 -.3 .9 .6 1.5 5.4
Electricity............. .6 .3 .4 -.2 .7 .0 1.2 3.6
Utility (piped) gas
service.............. .4 3.0 -.4 -.4 1.6 2.5 2.4 12.1
All items less food and
energy................. .1 .2 .0 .0 .1 .3 .9 3.0
Commodities less food and
energy commodities.... .0 .0 .1 .1 -.2 .1 2.0 4.4
New vehicles............ .3 .0 .4 -.5 .0 .0 .5 2.0
Used cars and trucks.... .9 -1.4 -.9 -.9 -.9 .5 10.0 21.0
Apparel................. -.9 .7 .9 2.2 -.7 -.3 .3 1.9
Medical care
commodities (1)...... -.7 -.4 -.2 -.1 -.7 .1 .6 -1.7
Services less energy
services.............. .1 .2 .0 .0 .2 .4 .5 2.5
Shelter................. .1 .1 .1 .1 .2 .3 .4 2.1
Transportation services .2 1.3 -.6 -.3 -.1 1.8 2.9 5.6
Medical care services... -.3 -.1 -.1 .5 .5 .1 .0 2.2