It could be that sound files for GTR are inefficiently large, however.
It's not just engine sounds though, it covers, exhaust pops/crackles, and other various sounds. What's funny is that some of the upper RPM sounds are pre pitch-shifted instead of a proper high RPM sample!

There is a bit of variety to add variation, which is welcome. Something that GT5 needs
Off course being easy to reach wav files makes it easy to mod. I might try substitue the LFA sound into of one these cars for laughs
For F3000
FOLDER E:\Games\GTR-Evolution\GameData\Sounds\Car\F3000\ 107 54,758,234
FILE 128,044 brakes_high_ex.wav
FILE 128,044 brakes_high_in.wav
FILE 76,844 brakes_low_ex.wav
FILE 76,844 brakes_low_in.wav
FILE 138,260 f3000_backfire_1.wav
FILE 66,238 f3000_backfire_2.wav
FILE 66,240 f3000_backfire_3.wav
FILE 778,536 F3000_dirt_roll_int.wav
FILE 17,362 f3000_downshift_1.wav
FILE 20,960 f3000_downshift_2.wav
FILE 19,968 f3000_downshift_3.wav
FILE 1,848,680 f3000_freehigh.wav
FILE 934,160 f3000_freelow.wav
FILE 818,428 f3000_freemax.wav
FILE 381,316 F3000_grass_roll_ext.wav
FILE 558,284 F3000_grass_roll_int.wav
FILE 779,300 F3000_grass_skid_ext.wav
FILE 1,558,556 F3000_grass_skid_int.wav
FILE 413,612 F3000_gravel_roll_ext.wav
FILE 1,209,708 F3000_gravel_roll_int.wav
FILE 779,342 F3000_gravel_skid_ext.wav
FILE 1,558,640 F3000_gravel_skid_int.wav
FILE 1,804,680 F3000_idle.wav
FILE 198,504 F3000_impact_car_heavy.wav
FILE 69,936 F3000_impact_car_light.wav
FILE 81,408 F3000_impact_car_medium.wav
FILE 70,908 F3000_impact_car_tap.wav
FILE 76,528 F3000_impact_car_verylight.wav
FILE 30,808 F3000_impact_cone.wav
FILE 365,168 F3000_impact_wall_heavy.wav
FILE 97,628 F3000_impact_wall_light.wav
FILE 113,692 F3000_impact_wall_medium.wav
FILE 48,892 F3000_impact_wall_tap.wav
FILE 59,096 F3000_impact_wall_verylight.wav
FILE 134,048 F3000_impactex_car_heavy.wav
FILE 67,480 F3000_impactex_car_light.wav
FILE 102,092 F3000_impactex_car_medium.wav
FILE 33,296 F3000_impactex_car_tap.wav
FILE 57,332 F3000_impactex_car_verylight.wav
FILE 31,140 F3000_impactex_cone.wav
FILE 143,936 F3000_impactex_wall_heavy.wav
FILE 124,392 F3000_impactex_wall_light.wav
FILE 101,644 F3000_impactex_wall_medium.wav
FILE 43,994 F3000_impactex_wall_tap.wav
FILE 66,436 F3000_impactex_wall_verylight.wav
FILE 23,350 F3000_limitertoggle_ext.wav
FILE 23,350 F3000_limitertoggle_int.wav
FILE 1,733,508 F3000_offhigh.wav
FILE 667,964 F3000_offlow.wav
FILE 1,370,500 f3000_offmax.wav
FILE 1,624,236 F3000_offmid.wav
FILE 1,100,236 F3000_on_fire_ext.wav
FILE 1,100,236 F3000_on_fire_int.wav
FILE 1,848,700 F3000_onhigh.wav
FILE 1,051,400 F3000_onlow.wav
FILE 1,848,700 f3000_onmax.wav
FILE 2,427,596 F3000_onmid.wav
FILE 1,247,636 F3000_rain.wav
FILE 383,356 F3000_revlimiter_ext.wav
FILE 383,356 F3000_revlimiter_int.wav
FILE 305,500 F3000_road_roll_ext.wav
FILE 690,988 F3000_road_roll_ext_wet.wav
FILE 1,473,536 F3000_road_roll_int.wav
FILE 1,653,980 F3000_road_roll_int_wet.wav
FILE 316,756 F3000_road_scrub_ext.wav
FILE 806,740 F3000_road_scrub_int.wav
FILE 510,280 F3000_road_skid_ext.wav
FILE 359,978 F3000_road_skid_ext_wet.wav
FILE 1,020,516 F3000_road_skid_int.wav
FILE 719,912 F3000_road_skid_int_wet.wav
FILE 1,903,620 F3000_roadstones.wav
FILE 951,832 F3000_roadstones_ext.wav
FILE 252,964 F3000_rumble.wav
FILE 252,964 F3000_rumble_ext.wav
FILE 326,036 F3000_scrape_ext.wav
FILE 326,036 F3000_scrape_int.wav
FILE 213,252 f3000_start.wav
FILE 722,448 f3000_startup.wav
FILE 18,870 f3000_upshift_1.wav
FILE 21,730 f3000_upshift_2.wav
FILE 26,480 f3000_upshift_3.wav
FILE 12,640 f3000_upshift_4.wav
FILE 68,050 f3000_whistle.wav
FILE 138,260 f3000ex_backfire_1.wav
FILE 66,238 f3000ex_backfire_2.wav
FILE 66,240 f3000ex_backfire_3.wav
FILE 25,290 f3000EX_downshift_1.wav
FILE 51,538 f3000EX_downshift_5.wav
FILE 28,380 f3000EX_downshift_7.wav
FILE 409,236 f3000ex_freehigh.wav
FILE 467,102 f3000ex_freelow.wav
FILE 924,368 f3000ex_freemax.wav
FILE 902,362 F3000ex_idle.wav
FILE 523,666 F3000ex_offhigh.wav
FILE 337,692 F3000ex_offlow.wav
FILE 685,272 f3000ex_offmax.wav
FILE 730,236 F3000ex_offmid.wav
FILE 924,368 F3000ex_onhigh.wav
FILE 529,714 F3000ex_onlow.wav
FILE 684,478 f3000ex_onmax.wav
FILE 523,228 F3000ex_onmid.wav
FILE 106,648 f3000ex_start.wav
FILE 342,084 f3000ex_startup.wav
FILE 51,538 f3000EX_upshift_1.wav
FILE 57,842 f3000EX_upshift_3.wav
FILE 61,280 f3000EX_upshift_4.wav
FILE 51,538 f3000EX_upshift_5.wav
For Mini Cooper
FOLDER E:\Games\GTR-Evolution\GameData\Sounds\Car\Cooper\ 42 13,525,972
FILE 64,044 cooper_backfire_1.wav
FILE 54,260 cooper_backfire_2.wav
FILE 270,976 cooper_backfire_3.wav
FILE 32,044 cooper_backfire_ext_1.wav
FILE 27,152 cooper_backfire_ext_2.wav
FILE 135,510 cooper_backfire_ext_3.wav
FILE 50,816 cooper_downshift_1.wav
FILE 76,756 cooper_downshift_2.wav
FILE 52,204 cooper_downshift_3.wav
FILE 25,430 cooper_downshift_ext_1.wav
FILE 38,400 cooper_downshift_ext_2.wav
FILE 52,204 cooper_downshift_ext_3.wav
FILE 226,100 cooper_freehigh.wav
FILE 605,872 cooper_freelow.wav
FILE 90,012 cooper_idle.wav
FILE 459,332 cooper_offhigh.wav
FILE 410,084 cooper_offlow.wav
FILE 447,672 cooper_offmid.wav
FILE 778,532 cooper_onhigh.wav
FILE 350,612 cooper_onlow.wav
FILE 1,194,196 cooper_onmid.wav
FILE 1,804,820 cooper_onveryhigh.wav
FILE 816,044 cooper_start.wav
FILE 816,044 cooper_startup.wav
FILE 58,080 cooper_upshift_1.wav
FILE 58,080 cooper_upshift_2.wav
FILE 58,076 cooper_upshift_3.wav
FILE 23,870 cooper_upshift_ext_1.wav
FILE 30,934 cooper_upshift_ext_2.wav
FILE 29,060 cooper_upshift_ext_3.wav
FILE 113,152 cooperex_freehigh.wav
FILE 302,608 cooperex_freelow.wav
FILE 45,028 cooperex_idle.wav
FILE 229,290 cooperex_offhigh.wav
FILE 204,828 cooperex_offlow.wav
FILE 226,562 cooperex_offmid.wav
FILE 389,288 cooperex_onhigh.wav
FILE 175,024 cooperex_onlow.wav
FILE 597,120 cooperex_onmid.wav
FILE 473,768 cooperex_onveryhigh.wav
FILE 816,044 cooperex_start.wav
FILE 816,044 cooperex_startup.wav