You need to indicate the full extent of the sensors and outputs.
A comment like suspension movement etc is rather vague as to total IO requirements.
Even for the suspension, is That in one axis only or in all three axis.
Then are the sensors going to be via i2c or direct to ADC inputs? Only one device per ADC input but can be many onto the i2c port (often 8 or more of the same i2c chip) and multiples of differing i2c chip types.
that may dictate a 28X2 or 40X2 part.
The X2 parts can operate to 64 MHz by design with an external resonator and even 80 or 100 MHz going outside the specs (I have 4 off 28X2 operating reliably at 80 MHz)
Think about your total IO and compare the count with the PICAXE pin out diagrams:
http://www.picaxe.com/What-is-PICAXE/PICAXE-Pinouts/
For any reasonable data logger you will either need several large 24/25LC series i2c EEPROM memory chips or to investigate use of SDRAM memory cards -there are a few past threads on the topic if you watch the forum.