The TG01 has a resistive screen, that means it can only record one button at a time.
(to be compared to capacitive screens, like the HD2's one, that can record two different points)
So you can't both accelerate and steer left/right at the same time.
You have different solutions to face it, depending on the game you're using and your personal preferences:
=> make the accelerate button sticky, that means once pressed, it will keep on accelerating until you press it again
=> Use the G-sensor to steer left-right, and accelerate with onscreen button
=> Use the G-sensor to accelerate/brake, and steer left/right with onscreen buttons (quite efficient once you're used to it)
=> Use multikey to make, for example, accelerate + left on the same button (but it's quite a mess, you need 6 directions buttons, left/right, left/right + accelerate, left/right + brake)
=> Use the "fake multitouch" portrait gamepad ( viewtopic.php?f=36&t=753
=> Make a fake multitouch landscape pad using the "middle point" trick (see cyber-junkie's "racing style PAD" here: viewtopic.php?f=36&t=565
=> Plug a simple USB gamepad into your TG01 using the microUSB/USB female adapter, the drivers cab is availiable in the TG01 section of the forum
=> Use a sixaxis or a wiimote via bluetooth with Cobaltikus drivers
=> Use the MSI BGP100 bluetooth gamepad (but now, this device is haaard to find and very expensive, nonsense!!!)